A046267 -id:A046267 - cp's OEIS frontend

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

Patrick De Geest, Jun 15 1998

nonn

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

Cf. A046267.

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 *)

A050730 Decimal expansion of 9^n contains no pair of consecutive equal digits (probably finite).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 7, 8, 9, 11, 12, 13, 21, 33

Offset: 0

Patrick De Geest, Sep 15 1999

			9^33 = 30903154382632612361920641803529.

Cf. A030705, A046267, A046275.

q:= n-> (s-> andmap(i-> s[i]<>s[i+1], [$1..length(s)-1]))(""||(9^n)):
select(q, [$0..200])[];  # Alois P. Heinz, Mar 07 2024

Select[Range[0,350],FreeQ[Differences[IntegerDigits[9^#]],0]&] (* Harvey P. Dale, Sep 16 2024 *)

cp's OEIS Frontend

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

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