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 A096448 #32 May 31 2024 03:53:07 %S A096448 5,11,17,23,31,41,47,59,67,103,127,419,431,439,461,467,1259,1279,1303, %T A096448 26833,26849,26881,26893,26921,26947,615883,616769,616787,616793, %U A096448 616829,617051,617059,617087,617257,617473,617509,617647,617681,617731,617819,617879 %N A096448 Primes p such that the number of primes less than p equal to 1 mod 4 is one less than the number of primes less than p equal to 3 mod 4. %H A096448 Michel Marcus, <a href="/A096448/b096448.txt">Table of n, a(n) for n = 1..751</a> %e A096448 First term prime(2) = 3 is placed on 0th row. %e A096448 If prime(n-1) = +1 mod 4 is on k-th row then we put prime(n) on (k-1)-st row. %e A096448 If prime(n-1) = -1 mod 4 is on k-th row then we put prime(n) on (k+1)-st row. %e A096448 This process makes an array of prime numbers: %e A096448 0th row: 3, 7, 19, 43, ... %e A096448 1st row: 5, 11, 17, 23, 31, 41, 47, 59, 67, 103, 127, ... %e A096448 2nd row: 13, 29, 37, 53, 61, 71, 79, 101, 107, 113 ... %e A096448 3rd row: 73, 83, 97, 109, ... %e A096448 4th row: 89, ... %t A096448 Prime[#]&/@(Flatten[Position[Accumulate[If[Mod[#,4]==1,1,-1]&/@ Prime[ Range[ 2,51000]]],-1]]+2) (* _Harvey P. Dale_, Mar 08 2015 *) %o A096448 (PARI) lista(nn) = my(vp=primes(nn), nb1=0, nb3=0); for (i=2, #vp, my(p = vp[i]); if (nb1 == nb3-1, print1(p, ", ")); if ((p % 4) == 1, nb1++, nb3++);); \\ _Michel Marcus_, May 30 2024 %Y A096448 Cf. A096447, A096449, A096450, A096451, A096452, A096453, A096454, A096455. %K A096448 nonn %O A096448 1,1 %A A096448 _Yasutoshi Kohmoto_, Aug 12 2004 %E A096448 More terms from _Joshua Zucker_, May 03 2006