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 A286159 #24 Jun 12 2025 12:57:26
%S A286159 1,1,3,1,4,6,1,4,3,10,1,4,8,7,15,1,4,8,3,6,21,1,4,8,13,7,11,28,1,4,8,
%T A286159 13,3,12,10,36,1,4,8,13,19,7,6,16,45,1,4,8,13,19,3,12,11,15,55,1,4,8,
%U A286159 13,19,26,7,18,17,22,66,1,4,8,13,19,26,3,12,6,10,21,78,1,4,8,13,19,26,34,7,18,11,16,29,91,1,4,8,13,19,26,34,3,12,25,17,23,28,105
%N A286159 Lower triangular region of array A286156, transposed.
%H A286159 Antti Karttunen, <a href="/A286159/b286159.txt">Table of n, a(n) for n = 1..10585; the first 145 rows of the triangle</a>
%e A286159 The first ten rows of this triangular array:
%e A286159 1,
%e A286159 1, 3,
%e A286159 1, 4, 6,
%e A286159 1, 4, 3, 10,
%e A286159 1, 4, 8, 7, 15,
%e A286159 1, 4, 8, 3, 6, 21,
%e A286159 1, 4, 8, 13, 7, 11, 28,
%e A286159 1, 4, 8, 13, 3, 12, 10, 36,
%e A286159 1, 4, 8, 13, 19, 7, 6, 16, 45,
%e A286159 1, 4, 8, 13, 19, 3, 12, 11, 15, 55
%t A286159 Map[((#1 + #2)^2 + 3 #1 + #2)/2 & @@ # & /@ Reverse@ # &, Table[Reverse@ QuotientRemainder[n, k], {n, 14}, {k, n}]] // Flatten (* _Michael De Vlieger_, May 20 2017 *)
%o A286159 (Scheme) (define (A286159 n) (A286156bi (A002024 n) (A004736 n))) ;; For A286156bi see A286156.
%o A286159 (Python)
%o A286159 def T(a, b): return ((a + b)**2 + 3*a + b)//2
%o A286159 def a(n, k): return T(n%k, n//k)
%o A286159 for n in range(1, 21): print([a(n , k) for k in range(1, n + 1)][::-1]) # _Indranil Ghosh_, May 20 2017
%Y A286159 Transpose: A268158.
%Y A286159 Cf. A000012, A000217, A268156, A268157.
%Y A286159 Rows converge towards A034856.
%K A286159 nonn,tabl
%O A286159 1,3
%A A286159 _Antti Karttunen_, May 04 2017