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 A371101 #8 Apr 19 2024 15:03:33
%S A371101 1,1,3,1,2,3,1,3,1,6,1,2,3,5,2,1,3,1,6,4,9,1,2,3,5,2,8,6,1,3,1,6,4,9,
%T A371101 2,12,1,2,3,5,2,8,6,11,1,1,3,1,6,4,9,2,12,7,15,1,2,3,5,2,8,6,11,1,14,
%U A371101 9,1,3,1,6,4,9,2,12,7,15,4,18,1,2,3,5,2,8,6,11,1,14,9,17,5,1,3,1,6,4,9,2,12,7,15,4,18,10,21
%N A371101 Array A read by upward antidiagonals in which the entry A(n,k) = A371092(A371100(n, k)), n,k >= 1.
%C A371101 A(n, k) gives the column index of A371100(n, k) in array A257852.
%F A371101 A(n, k) = A371092(A371100(n, k)).
%F A371101 A(n, k) = A(n+2, k).
%e A371101 The array begins:
%e A371101 n\k| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
%e A371101 ---+--------------------------------------------------------------------
%e A371101 1 | 1, 3, 3, 6, 2, 9, 6, 12, 1, 15, 9, 18, 5, 21, 12, 24, 4, 27, ...
%e A371101 2 | 1, 2, 1, 5, 4, 8, 2, 11, 7, 14, 4, 17, 10, 20, 1, 23, 13, 26, ...
%e A371101 3 | 1, 3, 3, 6, 2, 9, 6, 12, 1, 15, 9, 18, 5, 21, 12, 24, 4, 27, ...
%e A371101 4 | 1, 2, 1, 5, 4, 8, 2, 11, 7, 14, 4, 17, 10, 20, 1, 23, 13, 26, ...
%e A371101 5 | 1, 3, 3, 6, 2, 9, 6, 12, 1, 15, 9, 18, 5, 21, 12, 24, 4, 27, ...
%e A371101 6 | 1, 2, 1, 5, 4, 8, 2, 11, 7, 14, 4, 17, 10, 20, 1, 23, 13, 26, ...
%e A371101 7 | 1, 3, 3, 6, 2, 9, 6, 12, 1, 15, 9, 18, 5, 21, 12, 24, 4, 27, ...
%e A371101 8 | 1, 2, 1, 5, 4, 8, 2, 11, 7, 14, 4, 17, 10, 20, 1, 23, 13, 26, ...
%e A371101 ...
%o A371101 (PARI)
%o A371101 up_to = 105;
%o A371101 A000265(n) = (n>>valuation(n,2));
%o A371101 A371092(n) = floor((A000265(1+(3*n))+5)/6);
%o A371101 A371100sq(n,k) = 4^n*(6*k - 3 - 2*(-1)^n) + (4^n - 1)/3;
%o A371101 A371101sq(n,k) = A371092(A371100sq(n,k));
%o A371101 A371101list(up_to) = { my(v = vector(up_to), i=0); for(a=1,oo, for(col=1,a, i++; if(i > up_to, return(v)); v[i] = A371101sq((a-(col-1)),col))); (v); };
%o A371101 v371101 = A371101list(up_to);
%o A371101 A371101(n) = v371101[n];
%Y A371101 Cf. A257852, A371092, A371100.
%K A371101 nonn,tabl
%O A371101 1,3
%A A371101 _Antti Karttunen_, Apr 19 2024