%I #7 Mar 05 2019 00:14:25
%S 1,12,64,85,96,128,1510,1611,1812,2013,2114,2215,2416,2517,2618,2820,
%T 3021,3222,3424,3525,3626,3827,3928,4029,4230,4431,4532,4633,4834,
%U 4935,5036,5137,5238,5439,5540,5742,6044,6245,6346,6447,6548,6649,6850,6951
%N Nonprimes formed by concatenation of the decimal digits of a nonprime and its index.
%C Nonprimes of the form A141468(k)//k, where double slashes represent concatenation, sorted along increasing k.
%e A141468(n=1)//1 = 0//1 = 1 is not prime and inserted into the sequence.
%e A141468(n=2)//2 = 1//2 = 12 is not prime and inserted into the sequence.
%e A141468(n=3)//3 = 4//3 = 43 is prime and not inserted into the sequence.
%p cat2 := proc(a,b) dgs := max(1,ilog10(b)+1) ; a*10^dgs+b ; end:
%p n := 0 ; for c from 0 to 80 do if not isprime(c) then n := n + 1 ; if not isprime(cat2(c,n)) then printf("%d,", cat2(c,n)) ; fi; fi; od: # _R. J. Mathar_, Aug 03 2009
%Y Cf. A000040, A141468.
%K nonn,base
%O 1,2
%A _Juri-Stepan Gerasimov_, Jan 11 2009
%E Edited by _R. J. Mathar_, Aug 03 2009