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 A089986 #19 Feb 04 2024 01:16:58 %S A089986 -1,0,1,3,4,6,9,10,13,15,16,18,19,24,25,30,31,33,36,39,40,43,46,48,51, %T A089986 54,55,58,61,64,66,69,75,76,81,85,88,90,93,94,103,106,108,109,114,115, %U A089986 118,120,121,123,124,129,135,139,141,145,148,150,153,156,159,160,163,169 %N A089986 Numbers n such that 4n + 7 is prime. %D A089986 M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988. %D A089986 Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta,UTET, CittaStudiEdizioni, Milano 1997. %F A089986 a(n) = A005099(n) - 2 = A095278(n) - 1. %p A089986 A089986:=n->`if`(isprime(4*n+7), n, NULL): seq(A089986(n), n=-1..200); # _Wesley Ivan Hurt_, Sep 18 2014 %t A089986 Select[Range[-1, 200], PrimeQ[4 # + 7] &] (* _Wesley Ivan Hurt_, Sep 18 2014 *) %o A089986 (Magma) [ n: n in [-1..170] | IsPrime(4*n+7) ]; %o A089986 (PARI) is(n)=isprime(4*n+7) \\ _Charles R Greathouse IV_, Feb 20 2017 %Y A089986 Cf. A005099 ((( Primes = -1 mod 4 ) + 1)/4), A005098 (4n+1 is prime), A095278 (4n+3 is prime), A111215 (4n+5 is prime). %K A089986 sign %O A089986 1,4 %A A089986 _Giovanni Teofilatto_, Jan 13 2004 %E A089986 Edited and extended by _Klaus Brockhaus_, Dec 22 2008