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A103851 Numbers k such that 2*prime(k)+1, 2*prime(k+1)+1 and 2*prime(k+2)-1 are also consecutive primes. 2
2, 119, 372, 814, 4350, 9797, 16625, 16729, 40224, 45191, 48121, 63137, 71520, 83264, 89744, 94166, 103551, 109538, 111283, 113690, 117620, 232363, 265101, 268661, 269466, 302024, 316847, 329793, 333947, 334725, 340910, 352997, 380914, 381169, 384459, 385927 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
2*3+1 = 5, 2*5+1 = 7, 2*7 - 1 = 13; 3, 5 and 7 are consecutive primes as are 5, 7 and 13, so a(1) = 2 as 3 = prime(2).
MATHEMATICA
s={}; n=1; p1=2; p2=3; Do[p3 = NextPrime[p2]; If[PrimeQ[2*p1+1] && (np = NextPrime[2*p1+1]) == 2*p2+1 && NextPrime[np] == 2*p3-1, AppendTo[s, n]]; p1=p2; p2=p3; n++, {10^5}]; s (* Amiram Eldar, Jul 23 2021 *)
CROSSREFS
Cf. A103852.
Sequence in context: A013511 A013507 A013476 * A024030 A221231 A243512
KEYWORD
nonn
AUTHOR
Pierre CAMI, Feb 18 2005
EXTENSIONS
Corrected by T. D. Noe, Nov 02 2006
a(21) and a(30) inserted and a(36) added by Amiram Eldar, Jul 23 2021
STATUS
approved

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Last modified March 4 08:20 EST 2024. Contains 370522 sequences. (Running on oeis4.)