A379950 Numbers k such that k^2 is an odd primitive abundant number (A006038).

585, 32085, 41925, 46665, 121605, 134589, 181305, 212175, 388455, 495465, 544065, 839865, 1061565, 1152921, 1165515, 1243275, 1247103, 1335411, 1676829, 2151075, 2290869, 2478075, 2771835, 2838165, 3016725, 3122847, 3156795, 4571415, 4738041, 5153841, 5558985, 6125049, 7471425, 7676775, 7780101, 7822425, 8259867

Offset: 1

Author

Antti Karttunen, Jan 07 2025

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..3500 (terms 1..725 from Antti Karttunen)

Crossrefs

Square roots of A379949.

Subsequence of A174830.

Cf. A000196, A006038.

Programs

PARI

isok(k) = if(!(k % 2), 0, my(f = factor(k)); for(i = 1, #f~, f[i, 2] *= 2); if(sigma(f, -1) <= 2, return(0)); for(i = 1, #f~, f[i, 2] -= 1; if(sigma(f, -1) > 2, return(0)); f[i, 2] += 1); 1); \\ Amiram Eldar, Mar 12 2025

Formula

a(n) = A000196(A379949(n)).