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URL: https://oeis.org/A107414

⇱ A107414 - OEIS

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A107414
Least number k such that k*p(j)*p(j+1) - 1 and k*p(j)*p(j+1) + 1 are twin primes with p(j) and p(j+1) odd twin primes.
1
2, 12, 6, 60, 78, 336, 18, 216, 96, 144, 120, 18, 510, 516, 336, 66, 60, 420, 144, 570, 570, 270, 120, 156, 54, 102, 102, 540, 504, 48, 582, 264, 210, 156, 156, 78, 30, 282, 354, 240, 156, 372, 24, 102, 150, 180, 306, 690, 120, 210, 204, 252, 144, 156, 240, 156
OFFSET
1,1
LINKS
EXAMPLE
2*3*5=30 29 and 31 twin primes, 3 and 5 first odd twin primes so k(1)=2
12*5*7=420 419 and 421 twin primes, 5 and 7 second odd twin primes so k(2)=12
6*11*13=858 857 and 859 twin primes, 11 and 13 third odd twin primes k(3)=6
MATHEMATICA
Module[{tp=Times@@@Select[Partition[Prime[Range[500]], 2, 1] , #[[2]]-#[[1]] == 2&], len, k}, len=Length[tp]; Table[k=1; While[!And@@PrimeQ[k*tp[[n]]+{1, -1}], k++]; k, {n, len}]] (* Harvey P. Dale, Mar 04 2013 *)
CROSSREFS
Sequence in context: A086494 A388296 A354484 * A133437 A387002 A245692
KEYWORD
easy,nonn
AUTHOR
Pierre CAMI, May 26 2005
STATUS
approved