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

Author

Patrick De Geest, Jun 15 1998

Keywords

• nonn

Links

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

Crossrefs

Cf. A046267.

Programs

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 *)