A046275 Largest prime substring in 9^n (0 if none).

0, 0, 0, 29, 61, 9049, 53, 7829, 3046721, 89, 84401, 1381, 2429536481, 8329, 876792454961, 113209, 853020188851, 77181699666569, 15009463529, 35085171767, 2157665459056928801, 1094189891315123, 984770902183

Offset

0,4

Links

Harvey P. Dale, Table of n, a(n) for n = 0..100

Mathematica

lps[n_]:=Module[{c=9^n}, Max[Select[FromDigits/@Flatten[Table[ Partition[ IntegerDigits[c], i, 1], {i, IntegerLength[c]-1, 1, -1}], 1], PrimeQ]]]; Join[ {0, 0, 0}, Array[lps, 20, 3]] (* Harvey P. Dale, May 07 2015 *)

Crossrefs

Cf. A046267.

Sequence in context: A173032 A142047 A335329 * A092222 A338529 A039516

Adjacent sequences: A046272 A046273 A046274 * A046276 A046277 A046278

Keyword

nonn

Author

Patrick De Geest, Jun 15 1998

Status

approved