A029975 - OEIS

A029975

Primes that are palindromic in base 7.

2, 3, 5, 71, 107, 157, 257, 271, 307, 2549, 2647, 2801, 3347, 3697, 3851, 4201, 4397, 4649, 4951, 5399, 5651, 5749, 5903, 6449, 6701, 7451, 7703, 8053, 8501, 8753, 9103, 9551, 10007, 10357, 10903, 11057, 11953, 12157, 12409, 13109

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

P. De Geest, World!Of Palindromic Primes

MATHEMATICA

f[n_]:=FromDigits[RealDigits[n, 7][[1]]]==FromDigits[Reverse[RealDigits[n, 7][[1]]]]; lst={}; Do[p=Prime[n]; If[f[p], AppendTo[lst, p]], {n, 8!}]; lst (* Vladimir Joseph Stephan Orlovsky, Aug 10 2009 *)

pb7Q[n_]:=Module[{idn7=IntegerDigits[n, 7]}, idn7==Reverse[idn7]]; Select[ Prime[ Range[1600]], pb7Q] (* Harvey P. Dale, Nov 21 2015 *)

CROSSREFS

Sequence in context: A042239 A270582 A270916 * A042787 A270355 A041131

Adjacent sequences: A029972 A029973 A029974 * A029976 A029977 A029978

KEYWORD

nonn,base

AUTHOR

Patrick De Geest

STATUS

approved