%I #3 Feb 11 2014 19:05:29
%S 1,1,2,1,2,1,4,2,2,1,2,2,10,2,2,6,8,2,6,1,1,1,3,1,1,5,1,1,3,2,4,2,2,4,
%T 2,2,4,2,4,1,2,3,3,2,2,3,2,4,3,2,2,4,2,4,6,2,2,12,2,1,1,2,1,1,2,1,3,2,
%U 1,4,6,4,4,6,4,4,6,4,4,2,1,1,5,2,1,2,1,1,2,2,10,2,2,4,12,2,4,2,2,1,6,8
%N a(n) = the least natural number k such that k*reverse(n) + 1 is prime.
%C Conjecture: a(n) is less than or equal to n for all n.
%e Reverse(12) = 21 and the least natural number k such that 21 k + 1 is prime is k = 2; so a(12) = 2.
%t f[n_] := Module[{i}, i = 0; While[ ! PrimeQ[i*FromDigits[Reverse[IntegerDigits[n]]]+ 1], i++ ]; i]; Table[f[i], {i, 1, 150}]
%K base,nonn
%O 1,3
%A _Joseph L. Pe_, Jul 16 2002