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 A280265 #29 Jan 11 2020 15:57:47 %S A280265 3,2,0,1,1,3,3,2,1,1,3,4,4,4,4,3,5,6,9,27,3,6,8,16,256,3,7,10,25,3125, %T A280265 3,8,12,36,46656,3,9,14,49,823543,3,10,16,64,16777216,3,11,18,81, %U A280265 387420489,3,12,20,100,10000000000,3,13,22,121,285311670611,3,14,24,144,8916100448256 %N A280265 Array with five columns read by rows: H_k(n,2), with rows n >= 0 and columns 0 <= k <= 4, where H_n is the n-th hyperoperation. %C A280265 See A054871 for definitions and key links. %C A280265 The purpose of this sequence is to unify all the visible terms of the sequence: a(k)= H_k(n,2) for some n. %e A280265 Square array begins: %e A280265 3, 2, 0, 1, 1; %e A280265 3, 3, 2, 1, 1; %e A280265 3, 4, 4, 4, 4; %e A280265 3, 5, 6, 9, 27; %e A280265 3, 6, 8, 16, 256; %e A280265 3, 7, 10, 25, 3125; %e A280265 3, 8, 12, 36, 46656; %e A280265 3, 9, 14, 49, 823543; %e A280265 3, 10, 16, 64, 16777216; %e A280265 3, 11, 18, 81, 387420489; %e A280265 3, 12, 20, 100, 10000000000; %e A280265 3, 13, 22, 121, 285311670611; %e A280265 3, 14, 24, 144, 8916100448256; %e A280265 ... %e A280265 For row 10 we have: %e A280265 H_0(10,2) = 3; %e A280265 H_1(10,2) = 12; %e A280265 H_2(10,2) = 20; %e A280265 H_3(10,2) = 100; %e A280265 H_4(10,2) = 10000000000; %t A280265 H[0, x_, y_] := y + 1; %t A280265 H[1, x_, y_] := x + y; %t A280265 H[2, x_, y_] := x*y; %t A280265 H[3, x_, y_] := x^y; %t A280265 H[4, x_, 2] := x^x; %t A280265 Table[H[k, n, 2], {n, 0, 20}, {k, 0, 4}] %Y A280265 Cf. A054871, A256131 (contains only line n=10), A280267, A000312. %K A280265 nonn,tabf,easy %O A280265 0,1 %A A280265 _Natan Arie Consigli_, Dec 30 2016 %E A280265 Definition corrected by _Natan Arie Consigli_, Jun 13 2017