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 A249725 #15 Feb 06 2015 10:36:04
%S A249725 1,3,2,6,4,5,7,10,11,8,16,9,22,12,29,15,37,17,46,13,56,23,67,14,79,30,
%T A249725 92,18,106,38,121,21,137,47,154,24,172,57,191,19,211,68,232,31,254,80,
%U A249725 277,20,301,93,326,39,352,107,379,25,407,122,436,48,466,138,497,28,529,155,562,58,596,173,631,32,667,192,704,69,742,212,781,26,821,233,862,81
%N A249725 Inverse permutation to A135764.
%H A249725 Antti Karttunen, <a href="/A249725/b249725.txt">Table of n, a(n) for n = 1..10000</a>
%H A249725 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%F A249725 a(n) = 1 + (((A003602(n)+A007814(n))^2 + A007814(n) - A003602(n))/2).
%F A249725 As a composition of other permutations:
%F A249725 a(n) = A249742(A249811(n)).
%F A249725 a(n) = A246276(A246676(n)).
%F A249725 Other identities. For all n >= 0 the following holds:
%F A249725 a(A005408(n)) = A000124(n). [Maps odd numbers to central polygonal numbers].
%F A249725 a(A000079(n)) = A000217(n+1). [Maps powers of two to triangular numbers].
%o A249725 (Scheme) (define (A249725 n) (+ 1 (* (/ 1 2) (+ (expt (+ (A003602 n) (A007814 n)) 2) (- (A003602 n)) (A007814 n)))))
%o A249725 (PARI) a(n) = {r = 1; while(!(n%2), n = n >> 1; r++); k = 1 + n \ 2; binomial(r + k - 1, 2) + r} \\ _David A. Corneth_, Feb 05 2015
%Y A249725 Inverse: A135764.
%Y A249725 Similar or related permutations: A209268, A246276, A246676, A249742, A249811.
%Y A249725 Cf. A000079, A000124, A000217, A003602, A005408, A007814.
%K A249725 nonn
%O A249725 1,2
%A A249725 _Antti Karttunen_, Nov 15 2014