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 A254106 #6 Feb 06 2015 02:49:14 %S A254106 1,2,3,6,4,5,10,15,9,21,28,7,8,14,36,45,20,55,66,13,27,78,91,35,105, %T A254106 120,11,12,19,44,136,153,54,171,190,26,65,210,231,77,253,276,18,34,90, %U A254106 300,325,104,351,378,43,119,406,435,135,465,496,16,17,25,53,152,528,561,170,595,630,64,189,666,703,209,741,780,33,76 %N A254106 Inverse permutation to A254105. %H A254106 Antti Karttunen, <a href="/A254106/b254106.txt">Table of n, a(n) for n = 1..8192</a> %H A254106 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %o A254106 (Scheme) (define (A254106 n) (let ((col (A254112 n)) (row (A254111 n))) (* (/ 1 2) (- (expt (+ col row) 2) col row row row -2)))) %Y A254106 Inverse: A254105. %Y A254106 Cf. A254108, A254111, A254112. %K A254106 nonn %O A254106 1,2 %A A254106 _Antti Karttunen_, Jan 27 2015