A154561 Primes resulting from (sum of digits of k) + (sum of digits of prime(k)) as k runs through the positive integers.

3, 5, 11, 7, 13, 17, 23, 13, 23, 23, 13, 17, 23, 29, 19, 17, 29, 23, 17, 19, 23, 29, 23, 19, 31, 23, 17, 19, 29, 31, 31, 23, 11, 19, 19, 17, 19, 23, 17, 17, 17, 23, 29, 31, 23, 29, 23, 13, 19, 19, 31, 23, 23, 17, 11, 31, 23, 13, 23, 29, 23, 29, 29, 19, 23, 31, 37, 29, 37, 17

Offset: 1

Author

Juri-Stepan Gerasimov, Jan 12 2009

Keywords

• nonn
• base

Examples

			k=1 yields a term: prime(1) = 2 and 1 + 2 = 3 is prime, so a(1)=3;
k=2 yields a term: prime(2) = 3 and 2 + 3 = 5 is prime, so a(2)=5;
k=3 does not yield a term: prime(3) = 5 and 3 + 5 = 8 is composite;
k=4 yields a term: prime(4) = 7 and 4 + 7 = 11 is prime, so a(3)=11;
k=5 yields a term: prime(5) = 11 and 5 + 1 + 1 = 7 is prime, so a(4)=7.
		

Crossrefs

Cf. A000040.

Programs

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 isprime(a) then printf("%d,",a ) ; end if; end do: # R. J. Mathar, May 05 2010

Mathematica

sod[n_]:=Total[IntegerDigits[n]];Select[Table[sod[n]+sod[Prime[n]],{n,300}],PrimeQ] (* Harvey P. Dale, Dec 11 2012 *)

Extensions

Corrected from a(35) onwards by R. J. Mathar, May 05 2010

Name corrected and Example section edited by Jon E. Schoenfield, Feb 11 2019