A351536 Odd numbers for which sigma(k) is congruent to 2 modulo 4 and the 3-adic valuations of k and sigma(k) are equal.

13, 37, 61, 73, 97, 109, 153, 157, 181, 193, 229, 241, 277, 313, 325, 337, 349, 373, 397, 409, 421, 433, 457, 541, 577, 601, 613, 661, 673, 709, 733, 757, 769, 801, 829, 853, 877, 925, 937, 997, 1009, 1021, 1033, 1069, 1093, 1117, 1129, 1153, 1201, 1213, 1237, 1249, 1297, 1321, 1381, 1429, 1453, 1489, 1525, 1549

Offset

1,1

Links

Table of n, a(n) for n=1..60.

Index entries for sequences related to sigma(n)

Mathematica

Select[Range[1, 1500, 2], Mod[(s = DivisorSigma[1, #]), 4] == 2 && Equal @@ IntegerExponent[{#, s}, 3] &] (* Amiram Eldar, Feb 13 2022 *)

Prog

(PARI) isA351536(n) = if(!(n%2), 0, my(s=sigma(n)); (2 == (s%4)) && (valuation(n, 3) == valuation(s, 3)));

Crossrefs

Intersection of A191218 and A349749. Cf. A349755 (subsequence).

Cf. A000203, A007949, A351534.

Sequence in context: A140112 A089030 A351537 * A354467 A141122 A068228

Adjacent sequences: A351533 A351534 A351535 * A351537 A351538 A351539

Keyword

nonn

Author

Antti Karttunen, Feb 13 2022

Status

approved