A073805 Numbers k such that 1 + k*R(k) is prime, where R(k) is the reverse of k.

1, 2, 4, 6, 10, 16, 18, 20, 24, 25, 26, 28, 36, 42, 50, 52, 58, 61, 62, 63, 66, 68, 70, 80, 81, 82, 85, 86, 90, 100, 108, 112, 116, 120, 132, 136, 138, 140, 152, 162, 170, 190, 198, 200, 204, 205, 209, 210, 211, 213, 214, 219, 223, 224, 228, 231, 234, 236, 238

Offset

1,2

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

16 is a term because 16*61 + 1 = 977 is prime.

Maple

rev:= proc(n) local L, i;
  L:= convert(n, base, 10);
  add(L[-i]*10^(i-1), i=1..nops(L))
end proc:
filter:= t -> isprime(t*rev(t)+1):
select(filter, [$1..1000]); # Robert Israel, Jul 03 2024

Mathematica

Select[Range[250], PrimeQ[# IntegerReverse[#]+1]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Oct 05 2017 *)

Crossrefs

Cf. A004086, A061205.

Sequence in context: A134682 A327408 A083814 * A352587 A301374 A130320

Adjacent sequences: A073802 A073803 A073804 * A073806 A073807 A073808

Keyword

nonn,easy,base,look

Author

Shyam Sunder Gupta, Aug 23 2002

Status

approved