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A286381 Compound filter: a(n) = P(A055881(n), A278236(n)), where P(n,k) is sequence A000027 used as a pairing function. 2

%I

%S 2,5,16,12,67,9,16,23,436,80,1771,18,67,80,1771,668,16111,48,277,302,

%T 7141,2630,64621,14,16,23,436,80,1771,31,436,467,21946,1832,87991,94,

%U 1771,1832,87991,16292,793171,328,7141,7262,352381,64982,3173941,25,67,80,1771,668,16111,94,1771,1832,87991,16292,793171,706,16111,16292,793171,405452,19841851

%N Compound filter: a(n) = P(A055881(n), A278236(n)), where P(n,k) is sequence A000027 used as a pairing function.

%H Antti Karttunen, <a href="/A286381/b286381.txt">Table of n, a(n) for n = 1..10080</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PairingFunction.html">Pairing Function</a>

%H <a href="/index/Fa#facbase">Index entries for sequences related to factorial base representation</a>

%F a(n) = (1/2)*(2 + ((A055881(n)+A278236(n))^2) - A055881(n) - 3*A278236(n)).

%o (Scheme) (define (A286381 n) (* (/ 1 2) (+ (expt (+ (A055881 n) (A278236 n)) 2) (- (A055881 n)) (- (* 3 (A278236 n))) 2)))

%Y Cf. A000027, A055881, A278236, A286382, A286143.

%K nonn

%O 1,1

%A _Antti Karttunen_, May 08 2017

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Last modified July 22 02:02 EDT 2019. Contains 325210 sequences. (Running on oeis4.)