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 A077168 #18 May 08 2025 22:53:23 %S A077168 1,2,3,4,5,6,7,8,9,10,11,12,13,14,259200,15,16,17,18,19,87178291200, %T A077168 20,21,22,23,24,25,202741834014720,26,27,28,29,30,31,32, %U A077168 484725313854093312000000,33,34,35,36,37,38,39,40,4438779300500903005519872000000,41,42,43,44 %N A077168 Lexicographically earliest infinite sequence of distinct positive numbers with the property that when written as a triangle, the product of each row is a factorial. %C A077168 The old definition was "Triangle formed by grouping the natural numbers so that the n-th group contains n numbers whose product is a factorial.". - _N. J. A. Sloane_, Oct 06 2024 %e A077168 Triangle begins: %e A077168 1, %e A077168 2, 3, %e A077168 4, 5, 6, %e A077168 7, 8, 9, 10, %e A077168 11, 12, 13, 14, 259200, %e A077168 15, 16, 17, 18, 19, 87178291200, %e A077168 20, 21, 22, 23, 24, 25, 202741834014720, %e A077168 26, 27, 28, 29, 30, 31, 32, 484725313854093312000000, %e A077168 33, 34, 35, 36, 37, 38, 39, 40, 4438779300500903005519872000000, %e A077168 ... %e A077168 The row products are: %e A077168 1 = 1! %e A077168 2*3 = 6 = 3! %e A077168 4*5*6 = 120 = 5! %e A077168 7*8*9*10 = 5040 = 7! %e A077168 11*12*13*14*259200 = 6227020800 = 13! %e A077168 15*16*17*18*19*87178291200 = 121645100408832000 = 19! %e A077168 20*21*22*23*24*25*202741834014720 = 25852016738884976640000 = 23! %e A077168 26*27*28*29*30*31*32*484725313854093312000000 = 8222838654177922817725562880000000 = 31! %e A077168 33*34*35*36*37*38*39*40*4438779300500903005519872000000 = 37! %e A077168 ... %Y A077168 Cf. A076031, A077169, A077170, A077171. %K A077168 nonn,tabl %O A077168 0,2 %A A077168 _Amarnath Murthy_, Nov 01 2002 %E A077168 More terms from _Sascha Kurz_, Feb 10 2003 %E A077168 Entry revised by _N. J. A. Sloane_, Oct 06 2024