A154568 Composites of the form (sum of digits of k) + (sum of digits of prime(k)).

8, 10, 15, 18, 14, 12, 6, 9, 12, 15, 22, 16, 10, 20, 16, 10, 18, 21, 8, 14, 10, 20, 22, 16, 21, 26, 15, 22, 16, 18, 21, 26, 15, 24, 18, 14, 21, 15, 24, 22, 30, 20, 22, 15, 18, 20, 27, 26, 26, 24, 27, 34, 34, 21, 21, 22, 25, 32, 32, 28, 22, 27, 27, 36, 30, 25, 28, 18, 20, 18, 25

Offset

1,1

Links

Table of n, a(n) for n=1..71.

Example

Prime(3) = 5 and 3 + 5 = 8 is composite, so 8 is a term;
prime(6) = 13 and 6 + 1 + 3 = 10 is composite, so 10 is a term.

Maple

A007953 := proc(n) add(d, d=convert(n, base, 10)) ; end proc:
for n from 1 to 300 do a := A007953(n) +A007953(ithprime(n)) ; if a> 4 and not isprime(a) then printf("%d, ", a ) ; end if; end do: # R. J. Mathar, May 05 2010

Crossrefs

Cf. A000040, A002808.

Sequence in context: A100718 A063190 A101763 * A020940 A287557 A242732

Adjacent sequences: A154565 A154566 A154567 * A154569 A154570 A154571

Keyword

nonn,base

Author

Juri-Stepan Gerasimov, Jan 12 2009

Extensions

Corrected (a(36) changed, a(48) inserted etc.) by R. J. Mathar, May 05 2010

Status

approved