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A115685 Prime numbers whose digit reversal is a powerful(1) number (A001694). 1
23, 61, 163, 293, 487, 521, 691, 821, 1297, 1861, 2531, 2731, 4201, 4441, 4483, 5209, 5227, 8429, 8867, 9049, 9631, 12391, 14437, 16141, 16987, 25153, 25703, 29741, 52163, 61483, 63211, 65579, 65707, 65899, 67057, 67901, 69481, 80687 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
8867 is prime and 7688 = 2^3 * 31^2.
MAPLE
N:= 10000; # to get all entries <= N
F:= proc(p)
local L, i, q, f;
if not isprime(p) then return false end if;
L:= convert(p, base, 10);
q:= add(10^(i-1)*L[-i], i=1..nops(L));
f:= ifactors(q)[2];
not has(map2(op, 2, f), 1);
end proc;
select(F, [2*i+1 $ i=1..floor((N-1)/2)]);
# Robert Israel, Feb 11 2013
MATHEMATICA
fQ[n_] := Min[ Last@# & /@ FactorInteger@ FromDigits@ Reverse@ IntegerDigits@ n] > 1; Select[ Prime@ Range@ 8000, fQ] (* Robert G. Wilson v, Feb 11 2013 *)
CROSSREFS
Cf. A001694.
Sequence in context: A031342 A215166 A141870 * A069798 A067194 A355984
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Jan 31 2006
STATUS
approved

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Last modified February 24 05:49 EST 2024. Contains 370293 sequences. (Running on oeis4.)