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 A037260 #8 Jul 10 2015 22:48:20 %S A037260 1,3,9,26,62,127,233,393,621,932,1342,1869,2533,3355,4357,5562,6994, %T A037260 8678,10641,12911,15518,18493,21868,25676,29951,34728,40044,45937, %U A037260 52446,59611,67474,76078,85467,95686,106781,118799,131788,145797 %N A037260 a()=A037260 and its first [ A037261 ], 2nd [ A037262 ] and 3rd [ A037263 ] differences together include every number at most once and are monotonic and minimal. %C A037260 5 is the only number less than 100 not used in any of the 4 sequences - Larry Reeves (larryr(AT)acm.org), Sep 25 2000 %e A037260 After 1 3 9 26 62 %e A037260 ------ 2 6 17 36 %e A037260 ------- 4 11 19 %e A037260 -------- 7 8 %e A037260 the next free number is 10 which we CAN add to 4th row. %Y A037260 A037260-A037263 are 4-rowed analog of A037257-A037259. See A005228, A030124 for 2-rowed version. %K A037260 nonn,easy %O A037260 0,2 %A A037260 _N. J. A. Sloane_ %E A037260 More terms from Larry Reeves (larryr(AT)acm.org), Sep 25 2000