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A103804 Primes p such that both 2p +/- 21 are primes. +0
3
5, 13, 19, 29, 31, 41, 59, 79, 89, 101, 109, 131, 179, 211, 239, 241, 271, 311, 331, 349, 409, 421, 449, 499, 509, 521, 541, 601, 619, 701, 751, 821, 839, 881, 1009, 1091, 1181, 1201, 1319, 1321, 1399, 1429, 1459, 1489, 1531, 1571, 1619, 1801, 1949, 1951 (list; graph; listen)
OFFSET

1,1

COMMENT

If -11 is not prime (Mathematica considers -prime as prime), then the first term, 5, should be omitted.

FORMULA

p, 2p-21 and 2p+21 all are primes.

MATHEMATICA

Select[Range[2000], PrimeQ[ # ] && PrimeQ[2# + 21] && PrimeQ[2# - 21] &]

CROSSREFS

Cf. A103802, A103803.

Sequence in context: A118915 A084442 A023270 this_sequence A129919 A045454 A166575

Adjacent sequences: A103801 A103802 A103803 this_sequence A103805 A103806 A103807

KEYWORD

nonn

AUTHOR

Zak Seidov (zakseidov(AT)yahoo.com), Feb 16 2005

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Last modified December 21 10:15 EST 2009. Contains 171081 sequences.


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