A176590 - OEIS

%I #3 Mar 30 2012 19:00:24

%S 1,2,5,6,8,10,11,12,14,15,16,17,18,20,22,23,24,26,27,28,29,30,32,33,

%T 34,35,36,38,40,41,42,44,45,46,47,49,50,51,52,53,54,55,56,57,58,59,60,

%U 61,62,63,64,65,66,68,69,70,71,72,74,75,76,77,78,80,81,82,83,84,85,86,87,88

%N Numbers n such that both concatenation of divisors of n and reverse concatenation of divisors of n are nonprime.

%C See A037278(n) = concatenation of divisors of n and A176558(n) = reverse concatenation of divisors of n. See A176554, A175354. Sequence of corresponding values of concatenations of divisors of a(n): {1, 12, 15, 1236, 1248, 12510, 111, ...), sequence of corresponding values of reverse concatenations of divisors of a(n): {1, 21, 51, 6321, 8421, 10521, 111, ...).

%e For n = 6; a(6) = 10; divisors of 10: 1, 2, 5, 10; both concatenation of divisors 12510 and reverse concatenation of divisors 10521 are nonprime numbers.

%K nonn,base

%O 1,2

%A _Jaroslav Krizek_, Apr 21 2010

%E Extended and revised by _Charles R Greathouse IV_, Apr 24 2010