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 A286153 #16 Jun 11 2025 04:02:17
%S A286153 2,11,13,7,5,8,22,8,7,26,16,38,9,42,19,37,47,58,62,52,43,29,23,48,14,
%T A286153 51,25,34,56,30,39,19,16,41,33,64,46,80,31,25,20,23,32,88,53,79,93,
%U A286153 108,32,41,39,31,116,102,89,67,57,94,140,33,27,30,148,101,63,76,106,68,81,157,176,34,29,184,166,87,75,118,92,138,69,175,158,216,35,224,165,185,74,150,103
%N A286153 Square array read by descending antidiagonals A(1,1), A(1,2), A(2,1), ...: If n > k, A(n,k) = T(n XOR k, k), and otherwise A(n,k) = T(n, n XOR k), where T(n,k) is sequence A001477 considered as a two-dimensional table, and XOR is bitwise-xor (A003987).
%H A286153 Antti Karttunen, <a href="/A286153/b286153.txt">Table of n, a(n) for n = 1..10585; the first 145 antidiagonals of array</a>
%F A286153 A(n,k) = A286151(n,k), for n >= 1, k >= 1.
%F A286153 If n > k, A(n,k) = T(A003987(n,k),k), otherwise A(n,k) = T(n,A003987(n,k)), where T(n,k) is sequence A001477 considered as a two-dimensional table, and XOR is bitwise-xor (A003987).
%e A286153 The top left 1 .. 12 x 1 .. 12 corner of the array:
%e A286153 2, 11, 7, 22, 16, 37, 29, 56, 46, 79, 67, 106
%e A286153 13, 5, 8, 38, 47, 23, 30, 80, 93, 57, 68, 138
%e A286153 8, 7, 9, 58, 48, 39, 31, 108, 94, 81, 69, 174
%e A286153 26, 42, 62, 14, 19, 25, 32, 140, 157, 175, 194, 82
%e A286153 19, 52, 51, 16, 20, 41, 33, 176, 158, 215, 195, 110
%e A286153 43, 25, 41, 23, 39, 27, 34, 216, 237, 177, 196, 142
%e A286153 34, 33, 32, 31, 30, 29, 35, 260, 238, 217, 197, 178
%e A286153 64, 88, 116, 148, 184, 224, 268, 44, 53, 63, 74, 86
%e A286153 53, 102, 101, 166, 165, 246, 245, 46, 54, 87, 75, 114
%e A286153 89, 63, 87, 185, 225, 183, 223, 57, 81, 65, 76, 146
%e A286153 76, 75, 74, 205, 204, 203, 202, 69, 68, 67, 77, 182
%e A286153 118, 150, 186, 86, 114, 146, 182, 82, 110, 142, 178, 90
%t A286153 T[a_, b_]:=((a + b)^2 + 3a + b)/2; A[n_, k_]:=If[n>k,T[BitXor[n, k], k], T[n, BitXor[n, k]]]; Table[A[k, n - k + 1], {n, 20}, {k, n}] // Flatten (* _Indranil Ghosh_, May 21 2017 *)
%o A286153 (Scheme) (define (A286153 n) (A286151bi (A002260 n) (A004736 n))) ;; For A286151bi see A286151.
%o A286153 (Python)
%o A286153 def T(a, b): return ((a + b)**2 + 3*a + b)//2
%o A286153 def A(n, k): return T(n^k, k) if n>k else T(n, n^k)
%o A286153 for n in range(1, 21): print([A(k, n - k + 1) for k in range(1, n + 1)]) # _Indranil Ghosh_, May 21 2017
%Y A286153 Array A286151 without its topmost row and leftmost column.
%Y A286153 Cf. A003987, A091255, A286155.
%K A286153 nonn,tabl
%O A286153 1,1
%A A286153 _Antti Karttunen_, May 03 2017