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 A092360 #8 May 04 2021 01:06:52 %S A092360 0,1,1,3,5,8,13,14,28,43,45,89,135,138,143,284,430,438,451,897,1356, %T A092360 1404,1446,2878,4352,4423,4511,4645,9245,13979,14203,14476,14757, %U A092360 15184,30225,45693,46407,47275,48164,49512,98573,148982,151235,153968,156749 %N A092360 Spiro-tribonacci numbers: a(n) = sum of three previous terms that are nearest when terms arranged in a spiral. %e A092360 Terms are written in square boxes radiating spirally (cf. Ulam prime spiral). a(0) = 0, a(1) = 1 and a(2) = 1, so write 0, then 1 to its right, and another 1 below the first 1. The next unfilled box forms a square with the three filled boxes, so a(3) = a(0) + a(1) + a(2) = 0 + 1 + 1 = 2. %e A092360 . %e A092360 8--13--14--28 %e A092360 | %e A092360 5 0---1 %e A092360 | | %e A092360 3---2---1 %e A092360 . %e A092360 a(4) = 2 because a(0) + a(1) + a(2) = 0 + 1 + 1 = 2. %Y A092360 Cf. A078510, A092369. %K A092360 easy,nonn %O A092360 0,4 %A A092360 _Michael Joseph Halm_, Apr 02 2004; corrected Apr 05 2004