A319293 Numbers of the form 27^i*(9*j +- 1).

1, 8, 10, 17, 19, 26, 27, 28, 35, 37, 44, 46, 53, 55, 62, 64, 71, 73, 80, 82, 89, 91, 98, 100, 107, 109, 116, 118, 125, 127, 134, 136, 143, 145, 152, 154, 161, 163, 170, 172, 179, 181, 188, 190, 197, 199, 206, 208, 215, 216, 217, 224, 226, 233, 235, 242, 244

Offset

1,2

Comments

{+-a(n)} gives all nonzero cubes modulo all powers of 3, that is, cubes over 3-adic integers. So this sequence is closed under multiplication.

Links

Jianing Song, Table of n, a(n) for n = 1..9231 (all terms <= 40000)

Formula

a(n) = 13*n/3 + O(log(n)).

Prog

(PARI) isA319293(n)= n\27^valuation(n, 27)%9==1||n\27^valuation(n, 27)%9==8

Crossrefs

A056020 is a proper subsequence.

Perfect powers over 3-adic integers:

Squares: positive: A055047; negative: A055048 (negated);

Cubes: this sequence.

Sequence in context: A155966 A228072 A038209 * A061908 A056020 A049510

Adjacent sequences: A319290 A319291 A319292 * A319294 A319295 A319296

Keyword

nonn

Author

Jianing Song, Sep 16 2018

Status

approved