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 A056906 #24 Sep 08 2022 08:45:01 %S A056906 0,1,2,6,8,12,13,16,19,21,27,28,33,34,41,43,49,56,57,62,69,72,76,77, %T A056906 82,84,86,89,92,96,98,99,104,111,119,121,126,128,131,132,133,134,139, %U A056906 142,146,148,153,159,166,168,169,173,174 %N A056906 Numbers k such that 36*k^2 + 5 is prime. %C A056906 Except for a(1), a(n) is never a multiple of 5. %H A056906 Vincenzo Librandi, <a href="/A056906/b056906.txt">Table of n, a(n) for n = 1..1000</a> %F A056906 a(n) = sqrt(A056905(n)-5)/6. %e A056906 a(3)=2 since 36*2^2 + 5 = 149, which is prime. %t A056906 Select[Range[0,200],PrimeQ[36#^2+5]&] (* _Harvey P. Dale_, Jul 25 2011 *) %o A056906 (Magma) [n: n in [0..200]| IsPrime(36*n^2+5)]; // _Vincenzo Librandi_, Jul 14 2012 %o A056906 (PARI) is(n)=isprime(36*n^2+5) \\ _Charles R Greathouse IV_, Feb 17 2017 %Y A056906 This sequence and formula generate all primes of the form k^2+5, i.e., A056905. %Y A056906 Except for the first term, this sequence is a subsequence of A047201. %Y A056906 Cf. A056900, A056902. %K A056906 nonn,easy %O A056906 1,3 %A A056906 _Henry Bottomley_, Jul 07 2000 %E A056906 Offset corrected by _Arkadiusz Wesolowski_, Aug 09 2011