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A171255 Primes which are the average of two distinct Mersenne primes (A000668). 6
5, 17, 19, 67, 79, 4099, 4111, 4159, 65537, 65539, 65551, 65599, 262147, 266239, 1073741827, 1073741839, 1073807359, 309485009821345068724785151 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The subsequence of primes in A171253, which equals A171254 minus its subsequence A000668.
LINKS
FORMULA
EXAMPLE
a(n) = A171253(n) for n=1,2,3, since all of these terms are prime. The term A171253(4) = 65 is the first element of A171252 to be composite, and therefore not included in the present sequence A171255.
PROG
(PARI) select(isprime, concat(vector(#A00668, i, vector(i-1, j, A00668[i]+A00668[j])))/2) /* having defined A00668 as vector with initial terms of A000668. In PARI version 2.4.2, the syntax select( concat(...), x->isprime(x)) must be used. */
CROSSREFS
Cf. A171252, A171254 (includes elements of A000668).
Sequence in context: A153320 A171253 A226623 * A304540 A306125 A255901
KEYWORD
nonn
AUTHOR
M. F. Hasler, Mar 06 2010
STATUS
approved

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Last modified March 28 05:39 EDT 2024. Contains 371235 sequences. (Running on oeis4.)