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 A302826 #49 Feb 16 2025 08:33:53 %S A302826 1,2,0,4,0,4,0,2,0,10,0,4,0,3,0,16,0,6,0,5,0,10,0,10,0,5,0,13,0,14,0, %T A302826 3,0,10,0,16,0,7,0,40,0,8,0,6,0,26,0,12,0,9,0,19,0,14,0,9,0,34,0,21,0, %U A302826 5,0,19,0,36,0,13,0,28,0,18,0,7,0,31,0,18,0,19,0,34,0,15 %N A302826 a(n) is number of primes of form k^2 + n - k for 0 < k < n. %H A302826 Seiichi Manyama, <a href="/A302826/b302826.txt">Table of n, a(n) for n = 2..10000</a> %H A302826 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LuckyNumberofEuler.html">Lucky Number of Euler</a> %H A302826 Wikipedia, <a href="https://en.wikipedia.org/wiki/Lucky_numbers_of_Euler">Lucky numbers of Euler</a> %e A302826 Primes of form k^2 + n - k for 0 < k < n: %e A302826 n\k| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |a(n) %e A302826 ---+------------------------------------------------------------------------+---- %e A302826 2| 2; | 1 %e A302826 3| 3, 5; | 2 %e A302826 4| | 0 %e A302826 5| 5, 7, 11, 17; | 4 %e A302826 6| | 0 %e A302826 7| 7, , 13, 19, , 37; | 4 %e A302826 8| | 0 %e A302826 9| , 11, , , 29, , , ; | 2 %e A302826 10| | 0 %e A302826 11| 11, 13, 17, 23, 31, 41, 53, 67, 83, 101; | 10 %e A302826 12| | 0 %e A302826 13| 13, , 19, , , 43, , , , 103, , ; | 4 %e A302826 14| | 0 %e A302826 15| , 17, , , , , , 71, , , , , , 197; | 3 %e A302826 16| | 0 %e A302826 17| 17, 19, 23, 29, 37, 47, 59, 73, 89, 107, 127, 149, 173, 199, 227, 257; | 16 %Y A302826 Cf. A014556, A188424, A302445. %K A302826 nonn %O A302826 2,2 %A A302826 _Seiichi Manyama_, Apr 14 2018