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A165280 If p and q are twin primes then pq + 1 is always divisible by 3, except for (p,q)=(3,5). Sequence gives values of (pq + 1)/3. 1
12, 48, 108, 300, 588, 1200, 1728, 3468, 3888, 6348, 7500, 10800, 12288, 13068, 17328, 19200, 24300, 26508, 32448, 40368, 58800, 62208, 71148, 90828, 108300, 120000, 127308, 137388, 145200, 218700, 225228, 228528, 245388, 259308, 346800 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(n) = (A001359(n+1)*A006512(n+1)+1)/3 = (A037074(n+1)+1)/3 = A075369(n+1)/3. - Robert G. Wilson v, Sep 13 2009
MATHEMATICA
p = Rest@ Select[ Prime@ Range@ 175, PrimeQ[ # + 2] & ]; (p (p + 2) + 1)/3 (* Robert G. Wilson v, Sep 13 2009 *)
(Times@@#+1)/3&/@Select[Partition[Prime[Range[3, 200]], 2, 1], #[[2]]-#[[1]] == 2&] (* Harvey P. Dale, Aug 28 2022 *)
PROG
(Magma) [(p+1)^2 div 3: p in PrimesInInterval(5, 1100) |IsPrime(p+2)]; // Marius A. Burtea, Jan 02 2020
CROSSREFS
Sequence in context: A009958 A256695 A135453 * A280058 A173548 A006564
KEYWORD
nonn
AUTHOR
Tanin (Mirza Sabbir Hossain Beg) (mirzasabbirhossainbeg(AT)yahoo.com), Sep 13 2009
EXTENSIONS
More terms from Robert G. Wilson v, Sep 13 2009
Edited by N. J. A. Sloane, Sep 15 2009
STATUS
approved

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Last modified March 19 02:51 EDT 2024. Contains 370952 sequences. (Running on oeis4.)