A387723 Numbers k for which A107758(k) > 2*k, and also for some of the proper divisors d|k, d<k, A107758(d) > 2*d.

12, 18, 20, 24, 28, 30, 36, 40, 42, 44, 45, 48, 50, 52, 54, 56, 60, 66, 68, 70, 72, 75, 76, 78, 80, 84, 88, 90, 92, 96, 98, 100, 102, 104, 105, 108, 110, 112, 114, 116, 120, 124, 126, 130, 132, 135, 136, 138, 140, 144, 148, 150, 152, 154, 156, 160, 162, 164, 165, 168, 170, 172, 174, 176, 180, 182, 184, 186, 188

Offset

1,1

Comments

Not the same as positions of terms > 1 in A387725. For example, A387725(225) = 3, although 225 is not present in this sequence.

Links

Antti Karttunen, Table of n, a(n) for n = 1..10000

Prog

(PARI)
A107758(n) =  { my(f = factor(n)); prod(k=1, #f~, 1+sigma(f[k, 1]^f[k, 2])); };
is_A387723(n) = if((A107758(n)<=(2*n)), 0, fordiv(n, d, if(d<n && A107758(d)>(2*d), return(1))); (0));

Crossrefs

Cf. A107758, A387725.

Setwise difference A387721 \ A387722.

Cf. also A341610, A387713.

Sequence in context: A007624 A036456 A102467 * A389812 A342973 A126706

Adjacent sequences: A387720 A387721 A387722 * A387724 A387725 A387726

Keyword

nonn

Author

Antti Karttunen, Sep 06 2025

Status

approved