A341624 a(n) = 0 if n is a deficient number, otherwise a(n) is the number of nondeficient divisors of the last number in the iteration x -> A003961(x) (starting from x=n) for which that count (A341620) is nonzero.

0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 1, 0, 0, 0, 3, 0, 0, 0, 1, 0, 2, 0, 0, 0, 0, 0, 4, 0, 0, 0, 2, 0, 2, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 3, 0, 2, 0, 0, 0, 5, 0, 0, 0, 0, 0, 2, 0, 0, 0, 1, 0, 6, 0, 0, 0, 0, 0, 2, 0, 3, 0, 0, 0, 5, 0, 0, 0, 1, 0, 4, 0, 0, 0, 0, 0, 5, 0, 0, 0, 2, 0, 2, 0, 1, 0, 0, 0, 6, 0, 0, 0, 3, 0, 2, 0, 0, 0, 0, 0, 1

Offset

1,12

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for sequences computed from indices in prime factorization

Index entries for sequences related to sigma(n)

Prog

(PARI)
A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
A341620(n) = sumdiv(n, d, (sigma(d)>=(2*d)));
A341624(n) = { my(t, u=0); while((t=A341620(n))>0, u=t; n = A003961(n)); (u); };

Crossrefs

Cf. A005100 (positions of zeros).

Differs from A341620 for the first time at n=120, where a(120)=1, while A341620(120)=8.

Cf. also A341508, A341618.

Sequence in context: A143840 A028649 A305558 * A341620 A097798 A065205

Adjacent sequences: A341621 A341622 A341623 * A341625 A341626 A341627

Keyword

nonn

Author

Antti Karttunen, Feb 22 2021

Status

approved