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 A082466 Least k>=1 such that n^2+kn-1 and n^2+kn+1 are twin primes. 3
 3, 1, 1, 11, 1, 1, 53, 1, 3, 5, 7, 3, 11, 16, 1, 11, 43, 6, 11, 1, 1, 8, 13, 1, 17, 7, 3, 11, 43, 4, 11, 4, 7, 8, 31, 9, 17, 1, 9, 35, 1, 4, 53, 4, 7, 41, 43, 6, 23, 1, 17, 8, 67, 1, 5, 4, 17, 11, 1, 7, 197, 4, 3, 11, 25, 1, 227, 7, 3, 14, 157, 19, 11, 16, 3, 71, 43, 6, 53, 7, 7, 44, 31, 3, 41 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. J. Mathar, Table of n, a(n) for n = 1..1000 MAPLE A082466 := proc(n)     local k, p ;     for k from 1 do         p := (n+k)*n-1 ;         if isprime(p) and isprime(p+2) then             return k;         end if;     end do: end proc: # R. J. Mathar, Jul 20 2012 MATHEMATICA lk[n_]:=Module[{k=1}, While[!And@@PrimeQ[n^2+k*n+{1, -1}], k++]; k]; Array[ lk, 90] (* Harvey P. Dale, Nov 25 2013 *) PROG (PARI) a(n)=if(n<0, 0, k=1; while(isprime(n^2+k*n+1)*isprime(n^2+k*n-1)==0, s++); k) CROSSREFS Sequence in context: A100265 A086766 A078688 * A120270 A243752 A113711 Adjacent sequences:  A082463 A082464 A082465 * A082467 A082468 A082469 KEYWORD nonn AUTHOR Benoit Cloitre, Apr 27 2003 STATUS approved

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Last modified June 15 20:50 EDT 2019. Contains 324145 sequences. (Running on oeis4.)