A351534 Odd numbers for which sigma(k) is congruent to 2 modulo 4 and the 3-adic valuation of k is one larger than the 3-adic valuation of sigma(k).

45, 261, 369, 909, 1017, 1233, 1341, 1557, 2313, 2529, 2637, 2853, 3177, 3501, 3609, 4149, 4293, 4581, 5121, 5445, 5553, 5733, 5769, 5877, 6093, 6525, 6849, 7173, 7389, 7713, 8361, 8469, 8793, 9117, 9225, 9441, 9981, 10629, 10737, 10953, 11061, 11601, 11709, 12249, 12357, 12681, 12897, 13005, 13329, 13977, 14517

Offset

1,1

Links

Table of n, a(n) for n=1..51.

Index entries for sequences related to sigma(n)

Mathematica

Select[Range[1, 15000, 2], Mod[(s = DivisorSigma[1, #]), 4] == 2 && IntegerExponent[#, 3] - IntegerExponent[s, 3] == 1 &] (* Amiram Eldar, Feb 13 2022 *)

Prog

(PARI) isA351534(n) = if(!(n%2), 0, my(s=sigma(n)); (2 == (s%4)) && (valuation(n, 3) == (1+valuation(s, 3))));

Crossrefs

Subsequence of A351533, which is intersection of A008585 and A191218.

Cf. A000203, A007949, A351536.

Sequence in context: A127073 A089549 A178540 * A296326 A064561 A291177

Adjacent sequences: A351531 A351532 A351533 * A351535 A351536 A351537

Keyword

nonn

Author

Antti Karttunen, Feb 13 2022

Status

approved