A154520 The prime(n)-th digit of the concatenated nonprimes.

1, 4, 8, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 5, 5, 5, 5, 6, 6, 7, 7, 7, 7, 7, 8, 9, 9, 9, 9, 0, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 3, 1, 3, 4, 1, 4, 4, 4, 5, 1, 1, 5, 1, 6, 1, 6, 1, 7, 1, 1, 8, 1, 8, 8, 1, 1, 1, 0, 0, 2, 0, 2, 1, 2, 1, 2, 2, 2, 2, 2, 3, 2, 3, 3, 2, 4, 2, 4, 4, 5, 2, 2, 2, 6, 7, 7, 2

Offset: 1

Author

Juri-Stepan Gerasimov, Jan 11 2009

Keywords

• nonn
• base

Comments

The concatenated nonprimes A141468 are A129808 with an initial 0.

Crossrefs

Cf. A000040, A141468.

Programs

Maple

a129808 := [1] : for n from 4 to 400 do if not isprime(n) then a129808 := [op(a129808), op(ListTools[Reverse](convert(n,base,10))) ] ; fi; od:
for n from 1 do p := ithprime(n) ; printf("%d,", op(p-1,a129808) ) ; od: # R. J. Mathar, Aug 03 2009

Formula

a(n) = A129808(prime(n)-1) .

Extensions

Edited and extended by R. J. Mathar, Aug 03 2009