1,1

5^2=25 2+5=7

7^2=49 4+9=13

17^2=289 2+8+9=19

P:=proc(n) local i, k, w; for i from 1 by 1 to n do w:=0; k:=ithprime(i)^2; while k>0 do w:=w+(k-trunc(k/10)*10); k:=trunc(k/10); od; if isprime(w) then print(ithprime(i), w); fi; od; end: P(1000);

Sequence in context: A032412 A114970 A048710 this_sequence A019340 A018538 A038968

Adjacent sequences: A126139 A126140 A126141 this_sequence A126143 A126144 A126145

easy,nonn

Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Mar 07 2007