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A126142 Primes whose sum of the digits of their squares is also a prime. +0
1
5, 7, 17, 29, 37, 47, 53, 61, 73, 79, 83, 89, 107, 109, 127, 137, 149, 151, 173, 181, 199, 223, 263, 269, 271, 277, 281, 349, 367, 379, 389, 433, 443, 457, 461, 503, 521, 547, 557, 587, 601, 613, 673, 677, 683, 691, 701, 727, 739, 773, 827, 853, 857, 863, 887 (list; graph; listen)
OFFSET

1,1

EXAMPLE

5^2=25 2+5=7

7^2=49 4+9=13

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

MAPLE

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);

CROSSREFS

Sequence in context: A032412 A114970 A048710 this_sequence A019340 A018538 A038968

Adjacent sequences: A126139 A126140 A126141 this_sequence A126143 A126144 A126145

KEYWORD

easy,nonn

AUTHOR

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

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.


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