A337385 Odd numbers k for which A003973(k) >= 2*A003961(k).

334639305, 1003917915, 1265809545, 1353106755, 1673196525, 2109682575, 2255177925, 2342475135, 2553826275, 2691663975, 2729952225, 2953555605, 2982654675, 3011753745, 3128150025, 3157249095, 3234846615, 3258330075, 3419140725, 3442113675, 3681032355, 3797428635, 3855626775, 4059320265, 4292112825, 4350310965

Offset: 1

Author

Antti Karttunen, Aug 31 2020

Keywords

• nonn

Comments

Provided that there are no odd perfect numbers, then applying A003961 to each term and sorting into ascending order gives A115414.

Apparently, all terms are divisible by 255255 = 3*5*7*11*13*17. - Hugo Pfoertner, Sep 24 2020

Links

• Index entries for sequences computed from indices in prime factorization
• Index entries for sequences related to sigma(n)

Crossrefs

Subsequence of A337386.

Cf. A000203, A003961, A003973, A115414.

Programs

PARI

A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
isA337385(n) = if(!(n%2),0,my(x=A003961(n)); (sigma(x)>=2*x));