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 A046920 #17 Jul 22 2021 09:17:02 %S A046920 1,1,2,1,2,0,2,0,2,1,2,0,3,0,2,0,1,0,4,1,3,0,2,0,3,0,1,0,2,0,4,0,2,1, %T A046920 2,0,4,0,3,0,2,0,3,0,3,0,2,0,4,0,3,1,2,0,5,0,1,0,2,0,6,0,3,0,1,0,3,0, %U A046920 4,0,2,0,5,1,4,0,2,0,6,0,3,0,2,0,4,0,2,0,3,0,6,0,2,0,1,0,4,0,3 %N A046920 Number of ways to express n as p+2a^2; p = 1 or prime, a >= 0. %H A046920 T. D. Noe, <a href="/A046920/b046920.txt">Table of n, a(n) for n=1..10000</a> %H A046920 L. Hodges, <a href="https://www.jstor.org/stable/2690477">A lesser-known Goldbach conjecture</a>, Math. Mag., 66 (1993), 45-47. %H A046920 <a href="/index/Go#Goldbach">Index entries for sequences related to Goldbach conjecture</a> %o A046920 (Haskell) %o A046920 a046920 n = length $ filter ((\x -> x == 1 || a010051 x == 1) . (n -)) $ %o A046920 takeWhile (< n) a001105_list %o A046920 -- _Reinhard Zumkeller_, Apr 03 2013 %Y A046920 Cf. A042978, A046921, A046922, A046923, A060003, A143539. %Y A046920 Cf. A016067, A008578, A010051, A001105. %K A046920 nonn %O A046920 1,3 %A A046920 _David W. Wilson_