A365470 (2,6)-imperfect numbers.

6, 12, 24, 30, 60, 120, 252, 384, 510, 864, 1020, 1260, 1920, 2040, 2640, 5418, 12960, 21420, 21672, 32640, 75852, 98304, 108864, 131070, 262140, 346752, 379260, 491520, 524280, 1982988, 2296728, 5504940, 6447420, 8355840, 8388480, 36747648, 39009600, 57024000

Offset

1,1

Comments

Based on testing the first 38 terms, it seems this is a subsequence of Zumkeller numbers (A083207). - Ivan N. Ianakiev, Sep 12 2023

Links

Amiram Eldar, Table of n, a(n) for n = 1..56

László Tóth, A survey of the alternating sum-of-divisors function, arXiv:1111.4842 [math.NT], 2011-2014. See p. 7.

Mathematica

beta[n_]:=Sum[d*LiouvilleLambda[n/d], {d, Divisors[n]}]; Select[Range[5500], #==6*beta[beta[#]]&] (* Ivan N. Ianakiev, Sep 12 2023 *)

Prog

(PARI) beta(n) = sumdiv(n, d, d*(-1)^bigomega(n/d));
isok(k) = 6*beta(beta(k)) == k;

Crossrefs

Cf. A127725 (2-imperfect), A206367 ((2,3)-imperfect).

Cf. A206369 (beta).

Subsequence of A008588.

Sequence in context: A119500 A260633 A348632 * A110967 A000082 A263849

Adjacent sequences: A365467 A365468 A365469 * A365471 A365472 A365473

Keyword

nonn

Author

Michel Marcus, Sep 11 2023

Status

approved