A046272 Largest prime substring in 6^n (0 if none).

0, 0, 3, 2, 29, 7, 5, 7993, 67961, 769, 604661, 2797, 78233, 1306069, 783641, 7018498457, 2821109, 692665944473, 66841, 609359, 4400629, 21936950640377, 16217038422671, 3022305360281, 73838133832161689, 992970137, 170581728179

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. A046264.

Programs

Mathematica

Join[{0,0},Table[SelectFirst[Reverse[Union[FromDigits/@Flatten[Table[ Partition[ IntegerDigits[ 6^k],n,1],{n,IntegerLength[6^k]-1}],1]]],PrimeQ],{k,2,28}]] (* Harvey P. Dale, Mar 08 2023 *)