A359625 Least number m such that denominator(sigma(m)/(m+1)) = n, or zero if no such m exists.

2, 1, 8, 95, 4, 143, 6, 63, 26, 9, 10, 16415, 12, 111, 44, 255, 16, 273023, 18, 159, 62, 175, 22, 575, 74, 25, 80, 671, 28, 3599, 30, 511, 395, 441, 34, 5183, 36, 303, 116, 8639, 40, 163295, 42, 1055, 134, 101567, 46, 19191876318719, 48, 49, 152, 415, 52, 3887

Offset

1,1

Comments

First occurrence of n in A339966.

Links

Martin Ehrenstein, Table of n, a(n) for n = 1..10000 (first 1000 terms, except for n = 48, from Michel Marcus)

Formula

n | (a(n) + 1). - David A. Corneth, Jan 12 2023

Prog

(PARI) a(n) = my(k=1); while (denominator(sigma(k)/(k+1)) != n, k++); k;
(PARI) a(n) = if(n == 1, return(2)); my(k=n-1); while (denominator(sigma(k)/(k+1)) != n, k+=n); k; \\ David A. Corneth, Jan 12 2023

Crossrefs

Cf. A162657 (analog for sigma(m)/m), A339966.

Cf. A063906 (sigma(m)/(m+1) = 3/2)

Sequence in context: A239444 A224090 A013327 * A009349 A334254 A230582

Adjacent sequences: A359622 A359623 A359624 * A359626 A359627 A359628

Keyword

nonn

Author

Michel Marcus, Jan 07 2023

Extensions

a(48)-a(54) from Martin Ehrenstein, Jul 23 2023

Status

approved