%I #8 Feb 16 2025 08:33:45
%S 0,1,5,5,13,18,25,13,19,40,41,40,61,71,41,25,85,41,113,83,72,111,145,
%T 71,42,160,42,142,181,84,221,41,112,218,73,72,265,285,161,142,313,143,
%U 365,217,85,361,421,111,74,85,219,308,481,73,113,238,286,446,545,143,613,540,144,61,162,218,685,415,362,144,761,112,841,643,86,538,114,309,925,217
%N Compound filter: a(n) = P(A056239(n), A243503(n)), with a(1) = 0, where P(n,k) is sequence A000027 used as a pairing function.
%H Antti Karttunen, <a href="/A286456/b286456.txt">Table of n, a(n) for n = 1..8192</a> (computed by using the b-files of A056239 and A243503)
%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PairingFunction.html">Pairing Function</a>
%F a(1) = 0 and for n > 1, a(n) = (1/2)*(2 + ((A056239(n)+A243503(n))^2) - A056239(n) - 3*A243503(n)).
%o (Scheme) (define (A286456 n) (if (= 1 n) 0 (* (/ 1 2) (+ (expt (+ (A056239 n) (A243503 n)) 2) (- (A056239 n)) (- (* 3 (A243503 n))) 2))))
%Y Cf. A000027, A056239, A243503, A278520, A286454, A286455.
%K nonn,changed
%O 1,3
%A _Antti Karttunen_, May 14 2017