id:A068951 - OEIS Search Results

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Scan the primes, record digit-sum if it is itself prime.

+0
2

2, 3, 5, 7, 2, 5, 11, 5, 7, 11, 7, 13, 11, 17, 2, 5, 5, 11, 13, 7, 13, 11, 17, 11, 13, 17, 19, 7, 11, 13, 7, 11, 17, 11, 13, 5, 7, 11, 7, 13, 11, 17, 13, 19, 19, 5, 13, 7, 11, 17, 11, 13, 17, 19, 17, 13, 19, 17, 23, 7, 13, 11, 13, 17, 13, 17, 17, 13, 19, 13, 19, 17, 23, 17, 11, 13 (list; graph; listen)

	OFFSET	`1,1`
	EXAMPLE	`a(13)=5 since the 13th prime is 41, and 4+1=5, which is prime.`
	MAPLE	dig := X->convert((convert(X, base, 10)), `+`); a := n->`if`(isprime(dig(ithprime(n)))=true, dig(ithprime(n)), printf(""));
	CROSSREFS	`Cf. A046704.` `Sequence in context: A007605 A077765 A078400 this_sequence A139752 A004088 A126051` `Adjacent sequences: A068948 A068949 A068950 this_sequence A068952 A068953 A068954`
	KEYWORD	`easy,nonn,base`
	AUTHOR	`Francois Jooste (phukraut(AT)hotmail.com), Mar 10 2002`

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Last modified September 6 16:04 EDT 2008. Contains 143483 sequences.

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