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A289621 Compound filter (omega & bigomega): a(1) = 0, for n > 1, a(n) = P(A001221(n), A001222(n)), where P(n,k) is sequence A000027 used as a pairing function. 1

%I

%S 0,1,1,2,1,5,1,4,2,5,1,8,1,5,5,7,1,8,1,8,5,5,1,12,2,5,4,8,1,13,1,11,5,

%T 5,5,12,1,5,5,12,1,13,1,8,8,5,1,17,2,8,5,8,1,12,5,12,5,5,1,18,1,5,8,

%U 16,5,13,1,8,5,13,1,17,1,5,8,8,5,13,1,17,7,5,1,18,5,5,5,12,1,18,5,8,5,5,5,23,1,8,8

%N Compound filter (omega & bigomega): a(1) = 0, for n > 1, a(n) = P(A001221(n), A001222(n)), where P(n,k) is sequence A000027 used as a pairing function.

%H Antti Karttunen, <a href="/A289621/b289621.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>

%F a(1) = 0, for n > 1, a(n) = (1/2)*(2 + ((A001221(n)+A001222(n))^2) - A001221(n) - 3*A001222(n)).

%o (PARI) A289621(n) = if(1==n,0,(1/2)*(2 + ((omega(n)+bigomega(n))^2) - omega(n) - 3*bigomega(n)));

%o (Scheme) (define (A289621 n) (if (= 1 n) 0 (* (/ 1 2) (+ (expt (+ (A001221 n) (A001222 n)) 2) (- (A001221 n)) (- (* 3 (A001222 n))) 2))))

%Y Cf. A000027, A046523.

%Y Cf. A001221, A001222, A008966, A046660, A070012, A070013, A070014, A088529, A088530, A181591 (sequences with matching equivalence classes).

%K nonn

%O 1,4

%A _Antti Karttunen_, Jul 16 2017

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Last modified November 16 22:20 EST 2019. Contains 329208 sequences. (Running on oeis4.)