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 A286458 #11 Feb 16 2025 08:33:45 %S A286458 1,1,2,3,13,25,24,15,61,5,85,113,112,64,87,55,201,243,242,313,204,393, %T A286458 451,513,137,22,613,250,723,651,842,276,67,844,196,1015,1107,657,196, %U A286458 1253,1355,1020,1407,559,812,795,1744,1864,833,2051,1062,101,2181,1363,2384,2524,597,2741,2891,3045,3203,1935,1756,1081,1249,1938,3703,1534,441 %N A286458 Compound filter: a(n) = P(A286448(n), A286449(n)), where P(n,k) is sequence A000027 used as a pairing function. %C A286458 For all i, j: a(i) = a(j) => A286385(i) = A286385(j). %H A286458 Antti Karttunen, <a href="/A286458/b286458.txt">Table of n, a(n) for n = 1..10000</a> %H A286458 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PairingFunction.html">Pairing Function</a> %F A286458 a(n) = (1/2)*(2 + ((A286448(n)+A286449(n))^2) - A286448(n) - 3*A286449(n)). %F A286458 a(n) = A286459(A048673(n)). %o A286458 (Scheme) (define (A286458 n) (* (/ 1 2) (+ (expt (+ (A286448 n) (A286449 n)) 2) (- (A286448 n)) (- (* 3 (A286449 n))) 2))) %Y A286458 Cf. A000027, A033879, A048673, A252748, A286385, A286448, A286449, A286459. %K A286458 nonn %O A286458 1,3 %A A286458 _Antti Karttunen_, May 14 2017