This article covers the number 290. For the year, see 290.

290 (two hundred [and] ninety) is the natural number following 289 and preceding 291.

In mathematics

The product of three primes, 290 is a sphenic number, and the sum of four consecutive primes (67 + 71 + 73 + 79). The sum of the squares of the divisors of 17 is 290.

Not only is it a nontotient and a noncototient, it is also an untouchable number.

290 is the 16th member of the Mian–Chowla sequence; it can not be obtained as the sum of any two previous terms in the sequence.[1]

See also the Bhargava–Hanke 290 theorem.

Integers from 291 to 299

291

291 = 3·97, a semiprime, floor(3^14/2^14) (sequence A002379 in the OEIS).

292

292 = 22·73, a noncototient, untouchable number. The continued fraction representation of is [3; 7, 15, 1, 292, 1, 1, 1, 2...]; the convergent obtained by truncating before the surprisingly large term 292 yields the excellent rational approximation 355/113 to , repdigit in base 8 (444).

293

293 is prime, Sophie Germain prime, Chen prime, Irregular prime, Eisenstein prime with no imaginary part, and a strictly non-palindromic number.

294

294 = 2·3·72, the number of rooted trees with 28 vertices in which vertices at the same level have the same degree (sequence A003238 in the OEIS).

295

295 = 5·59, a centered tetrahedral number

296

296 = 23·37, a refactorable number, unique period in base 2, the number of regions formed by drawing the line segments connecting any two of the 12 perimeter points of an 2 times 4 grid of squares (illustration) (sequence A331452 in the OEIS), and the number of surface points on a 83 cube.[2]

297

297 = 33·11, the number of integer partitions of 17, a decagonal number, and a Kaprekar number

298

298 = 2·149, is nontotient, noncototient, and the number of polynomial symmetric functions of matrix of order 6 under separate row and column permutations[3]

299

299 = 13·23, a highly cototient number, a self number, and the twelfth cake number

References

  1. ^ "Sloane's A005282 : Mian-Chowla sequence". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-28.
  2. ^ Sloane, N. J. A. (ed.). "Sequence A005897". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  3. ^ Sloane, N. J. A. (ed.). "Sequence A007716 (Number of polynomial symmetric functions of matrix of order n under separate row and column permutations)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.