This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A271428 #14 Dec 17 2024 22:54:20 %S A271428 3,6,24,42,48,86,102,138,182,302,438,506,926,1266,3600,23550,24122, %T A271428 42410,51432,82290,137246 %N 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). %C A271428 a(21) > 10^5. - _Robert Price_, Apr 14 2016 %e A271428 6 is in the sequence because F(6)*F(7)-1 = 8*13-1 = 103, which is prime. %t A271428 Select[Range[5 * 10^3], PrimeQ[Fibonacci@ # Fibonacci[# + 1] - 1] &] (* _Michael De Vlieger_, Apr 07 2016 *) %o A271428 (PARI) L=List(); for(k=1, 1000, if(ispseudoprime(fibonacci(k)*fibonacci(k+1)-1), listput(L, k))); Vec(L) %Y A271428 Cf. A000045, A271427. %K A271428 nonn,more %O A271428 1,1 %A A271428 _Colin Barker_, Apr 07 2016 %E A271428 a(15) from _Michael De Vlieger_, Apr 07 2016 %E A271428 a(16)-a(20) from _Robert Price_, Apr 14 2016 %E A271428 a(21) from _Michael S. Branicky_, Dec 17 2024