A098475 a(n) is the smallest integer k for which sigma_n(k) <= sigma_n(k-1) where sigma_n(k) = sum of the n-th powers of the divisors of k.

3, 5, 7, 25, 61, 145, 361, 853, 1969, 4489, 10069, 22273, 48781, 105949, 228589, 490405, 1046977, 2225965, 4715401, 9956977, 20965213, 44031361, 92262349, 192920785, 402629257, 838827577, 1744784389, 3623814865, 7516104565

Offset

0,1

Comments

a(n) has to be larger than the solution to Zeta(n)*(x-1)^n=x^n.

Links

Table of n, a(n) for n=0..28.

Example

a(1)=5 since sigma(1)=1,sigma(2)=3,sigma(3)=4, sigma(4)=7, but sigma(5)=6.

Prog

(PARI) a(n) = {my(k = 2); while(sigma(k, n) > sigma(k-1, n), k++); k; } \\ Michel Marcus, Aug 18 2013

Crossrefs

Sequence in context: A045966 A374670 A146148 * A131039 A362684 A294924

Adjacent sequences: A098472 A098473 A098474 * A098476 A098477 A098478

Keyword

nonn

Author

John L. Drost, Oct 26 2004

Status

approved