A387165 Nondeficient numbers k for which A324644(k)/A324198(k) = 2.

38745, 77805, 78435, 118755, 141075, 157815, 210735, 237195, 241605, 294975, 300105, 323505, 364455, 371925, 390195, 409185, 455715, 475335, 499905, 567945, 607635, 660825, 701415, 733005, 766395, 806085, 809325, 872235, 885465, 891135, 937755, 964845, 978705, 1101555, 1150065, 1201095, 1229445, 1265355, 1293705

Offset: 1

Author

Antti Karttunen, Aug 28 2025

Keywords

• nonn
• new

Comments

First three nonmultiples of 5 occur at a(138), a(276), a(356) = 4446981, 8909901, 11234223. (Cf. A005231, A064001).

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to primorial base
• Index entries for sequences related to sigma(n)
• Index entries for sequences where odd perfect numbers must occur, if they exist at all

Crossrefs

Intersection of A023196 and A364286.

Cf. A000203, A276086.

Cf. also A371082, A386422, A387163 and A047802, A064001, A115414.

Programs

PARI

A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
is_A387165(n) = if(sigma(n)<2*n, 0, my(u=A276086(n)); (gcd(sigma(n),u)==2*gcd(n,u)));

Formula

{k | sigma(k) >= 2*k, A324644(k) = 2*A324198(k)}.