A292626 Numbers k whose abundance is 128: sigma(k) - 2*k = 128.

860, 5336, 6536, 9656, 16256, 55796, 70864, 98048, 361556, 776096, 2227616, 4145216, 4498136, 4632896, 8124416, 13086016, 34869056, 38546576, 150094976, 172960856, 196066256, 962085536, 1080008576, 1733780336, 1844788112, 2143256576, 2531343872, 2986104064, 9677743616, 11276687456, 17104503968, 20680182272, 21568135616

Offset

1,1

Links

Max Alekseyev, Table of n, a(n) for n = 1..111 (terms below 10^20)

Mathematica

fQ[n_] := DivisorSigma[1, n] == 2 n + 128; Select[ Range@ 10^8, fQ] (* Robert G. Wilson v, Nov 19 2017 *)

Prog

(PARI) isok(n) = sigma(n) - 2*n == 128; \\ Michel Marcus, Sep 20 2017

Crossrefs

Subsequence of A259174.

Deficiency k: A191363 (k=2), A125246 (k=4), A141548 (k=6), A125247 (k=8), A101223 (k=10), A141549 (k=12), A141550 (k=14), A125248 (k=16), A223608 (k=18), A223607 (k=20), A223606 (k=22), A385255(k=24), A275702 (k=26), A387352 (k=32), A175730 (k=42), A101259 (k=54), A275997 (k=64).

Abundance k: A088831 (k=2), A088832 (k=4), A087167 (k=6), A088833 (k=8), A223609 (k=10), A141545 (k=12), A141546 (k=14), A141547 (k=16), A223610 (k=18), A223611 (k=20), A223612 (k=22), A223613 (k=24), A275701 (k=26), A175989 (k=32), A275996 (k=64).

Sequence in context: A108822 A278156 A249461 * A115749 A105323 A206756

Adjacent sequences: A292623 A292624 A292625 * A292627 A292628 A292629

Keyword

nonn

Author

Fabian Schneider, Sep 20 2017

Extensions

a(9)-a(18) from Michel Marcus, Sep 20 2017

a(19)-a(24), a(26), a(29)-a(30), a(33) from Robert G. Wilson v, Nov 20 2017

Missing terms a(25), a(27)-a(28), a(31)-a(32) inserted and terms a(34) onward added by Max Alekseyev, Aug 30 2025

Status

approved