A120805 - OEIS

%I #4 Mar 30 2012 17:31:20

%S 2,3,5,7,23,43,67,89,109,4567,10987,76543,78901,678901,23456789,

%T 45678901,9012345678901,789012345678901,56789012345678901234567890123,

%U 90123456789012345678901234567,10987654321098765432109876543210987

%N Primes with consecutive digits.

%C Digits can be in ascending or descending order. After 9 comes 0 or after 0 comes 1.

%C The number of primes with n consecutive digits: 4,4,1,1,3,1,0,2,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,1,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,...,.

%t f[n_] := Block[{u = Range@n, d = Reverse@ Range@n, t = Table[1, {n}]}, Select[ Drop[ Union@ Flatten@ Table[ FromDigits /@ Mod[{u, d} + {i*t, i*t}, 10], {i, 10}], 2], PrimeQ@# &]]; Array[f, 35] // Flatten

%Y Cf. A000040, A118697; union of A006055 & A120804.

%K nonn,base

%O 1,1

%A _Robert G. Wilson v_, Jul 05 2006