A348931 Numbers k congruent to 1 or 5 mod 6, for which A348930(k) < k.

5, 11, 17, 23, 29, 35, 41, 47, 49, 53, 55, 59, 65, 71, 77, 83, 85, 89, 95, 101, 107, 113, 115, 119, 125, 131, 137, 143, 145, 149, 155, 161, 167, 169, 173, 179, 185, 187, 191, 197, 203, 205, 209, 215, 221, 227, 233, 235, 239, 245, 251, 253, 257, 263, 265, 269, 275, 281, 287, 293, 295, 299, 305, 311, 317, 319, 323

Offset

1,1

Comments

See comments in A348930.

Links

Table of n, a(n) for n=1..67.

Index entries for sequences related to sigma(n)

Mathematica

s[n_] := n / 3^IntegerExponent[n, 3]; Select[Range[350], MemberQ[{1, 5}, Mod[#, 6]] && s[DivisorSigma[1, #]] < # &] (* Amiram Eldar, Nov 04 2021 *)

Prog

(PARI)
A038502(n) = (n/3^valuation(n, 3));
A348930(n) = A038502(sigma(n));
isA348931(n) = ((n%2)&&(n%3)&&(A348930(n)<n));

Crossrefs

Cf. A007310, A348930, A348932, A348933.

Cf. also A348741, A348753.

Sequence in context: A172332 A314250 A105644 * A314251 A314252 A314253

Adjacent sequences: A348928 A348929 A348930 * A348932 A348933 A348934

Keyword

nonn

Author

Antti Karttunen, Nov 04 2021

Status

approved