A130181 Largest k > 1 such that (sum of digits of k^n)*(sum of digits of k^(n+1)) = k, or 0 if no such k exists.

486, 1215, 4374, 4672, 12862, 12649, 23408, 32761, 47477, 56852, 59048, 90746, 116864, 112346, 139472, 149705, 190512, 234247, 254015, 0, 322322, 331775, 391238, 446512, 454951, 546121, 530145, 316250, 613927, 763795, 786664, 809936

Offset

1,1

Links

Klaus Brockhaus, Table of n, a(n) for n=1..54

Example

For n = 2 the largest such k is 1215: 1215^2 = 1476225 and 1+4+7+6+2+2+5 = 27; 1215^3 = 1793613375and 1+7+9+3+6+1+3+3+7+5 = 45; 27*45 = 1215. Hence a(2) = 1215.

Crossrefs

Cf. A126783 (smallest k), A130179 (upper bound), A130180 (number of such k).

Sequence in context: A031520 A235525 A249227 * A158325 A187860 A205240

Adjacent sequences: A130178 A130179 A130180 * A130182 A130183 A130184

Keyword

nonn,base

Author

Klaus Brockhaus, May 14 2007

Status

approved