A348932 Numbers k congruent to 1 or 5 mod 6, for which A348930(k) > k.

7, 13, 19, 25, 31, 37, 43, 61, 67, 73, 79, 91, 97, 103, 109, 121, 127, 133, 139, 151, 157, 163, 175, 181, 193, 199, 211, 217, 223, 229, 241, 247, 259, 271, 277, 283, 289, 301, 307, 313, 325, 331, 337, 343, 349, 367, 373, 379, 397, 403, 409, 421, 427, 433, 439, 457, 463, 469, 475, 481, 487, 499, 511, 523, 529, 541

Offset: 1

Author

Antti Karttunen, Nov 04 2021

Keywords

• nonn

Comments

See comments in A348930.

Links

• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A007310, A348930, A348931.

Cf. also A348742, A348754.

Programs

Mathematica

s[n_] := n / 3^IntegerExponent[n, 3]; Select[Range[550], MemberQ[{1, 5}, Mod[#, 6]] && s[DivisorSigma[1, #]] > # &] (* Amiram Eldar, Nov 04 2021 *)

PARI

A038502(n) = (n/3^valuation(n, 3));
A348930(n) = A038502(sigma(n));
isA348932(n) = ((n%2)&&(n%3)&&(A348930(n)>n));