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 A271428 Values of k such that F(k)*F(k+1)-1 is a prime, where F(k) is the k-th Fibonacci number (A000045). 1
 3, 6, 24, 42, 48, 86, 102, 138, 182, 302, 438, 506, 926, 1266, 3600, 23550, 24122, 42410, 51432, 82290 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(21) > 10^5. - Robert Price, Apr 14 2016 LINKS EXAMPLE 6 is in the sequence because F(6)*F(7)-1 = 8*13-1 = 103, which is prime. MATHEMATICA Select[Range[5 * 10^3], PrimeQ[Fibonacci@ # Fibonacci[# + 1] - 1] &] (* Michael De Vlieger, Apr 07 2016 *) PROG (PARI) L=List(); for(k=1, 1000, if(ispseudoprime(fibonacci(k)*fibonacci(k+1)-1), listput(L, k))); Vec(L) CROSSREFS Cf. A000045, A271427. Sequence in context: A106213 A129520 A047167 * A148649 A148650 A148651 Adjacent sequences:  A271425 A271426 A271427 * A271429 A271430 A271431 KEYWORD nonn,more AUTHOR Colin Barker, Apr 07 2016 EXTENSIONS a(15) from Michael De Vlieger, Apr 07 2016 a(16)-a(20) from Robert Price, Apr 14 2016 STATUS approved

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Last modified December 13 22:42 EST 2018. Contains 318087 sequences. (Running on oeis4.)