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A138790 a(n) = indices n for which A138793(n) is prime. 17
61, 946 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Indices where number 1 occured in A138789

There are no more primes for n<=5000

EXAMPLE

a(1)=61 because the number 16069585756555453525150594847464544434241404938373635343332313039282726252423222120291817161514131211101987654321 is prime

MATHEMATICA

b = {}; a = {}; Do[w = RealDigits[n]; w = First[w]; Do[AppendTo[a, w[[k]]], {k, 1, Length[w]}]; p = FromDigits[Reverse[a]]; If[PrimeQ[p], Print[n]; AppendTo[b, p]], {n, 1, 2000}]; b (*Artur Jasinski*)

CROSSREFS

Cf. A000422, A116504, A007908, A116505, A138793, A138789.

Sequence in context: A093473 A000506 A008358 * A057534 A152868 A154428

Adjacent sequences:  A138787 A138788 A138789 * A138791 A138792 A138793

KEYWORD

nonn,bref,more,base

AUTHOR

Artur Jasinski (grafix(AT)csl.pl), Mar 30 2008, Mar 31 2008

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Last modified February 15 21:56 EST 2012. Contains 205860 sequences.