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 A367339 #20 Jan 20 2024 08:50:24 %S A367339 11,22,33,44,56,67,78,89,91,1,12,23,34,45,57,68,79,-1,91,2,13,24,35, %T A367339 47,58,69,-1,81,91,3,14,25,36,48,59,-1,71,81,91,4,15,26,38,49,-1,61, %U A367339 71,81,91,5,16,27,39,-1,51,61,71,81,91,6,17,29,-1,41,51,61,71,81,91,7,18,-1 %N A367339 a(n) = A367338(n) - n, or -1 if A367338(n) = -1. %C A367339 Construct the commas sequence as in A121805, but take first term to be n. Then a(n) is the two digit number surrounding the first comma, or -1 if there is no second term (and hence no comma). %C A367339 a(n) (unless it -1) is called the comma-number of n. %C A367339 As in A121805, if the term before the comma ends in 0, that 0 is ignored and the comma number is a single-digit number. %H A367339 N. J. A. Sloane, <a href="/A367339/b367339.txt">Table of n, a(n) for n = 1..10000</a> %e A367339 For n = 1, A121805 begins 1, 12, 35, 94, ..., and the first comma appears as 1,1, so a(1) = 11. %e A367339 For n = 2, A139284 begins 2, 24, 71, 89, ... and the first comma appears as 2,2, so a(2) = 22. %e A367339 For n = 36, the commas sequence starting at 36 is simply the one-term sequence [36], no second term exists, there is no comma, and so a(36) = -1. %Y A367339 Cf. A121805, A367338, A367340, A367341. %K A367339 sign,base %O A367339 1,1 %A A367339 _N. J. A. Sloane_, Nov 15 2023