1,1

A128358(n) begins {1, 17, 289, 4913, 83521, 1419857, 5846759, 24054337, 24137569, ...} = {1, 17, 17^2, 17^3, 17^4, 17^5, 20231*17^2, 83233*17^2, 17^6, ...}.

Thus a(1) = 17, a(2) = 20231, a(3) = 83233.

Cf. A128356, A128357, A128358 = Numbers n such that n divides 18^n - 1.

Sequence in context: A079687 A062659 A114924 this_sequence A110915 A068733 A066161

Adjacent sequences: A134357 A134358 A134359 this_sequence A134361 A134362 A134363

bref,hard,more,nonn

Alexander Adamchuk (alex(AT)kolmogorov.com), Jan 31 2008