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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
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, 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, 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
OFFSET
1,4
FORMULA
a(1) = 0, for n > 1, a(n) = (1/2)*(2 + ((A001221(n)+A001222(n))^2) - A001221(n) - 3*A001222(n)).
PROG
(PARI) A289621(n) = if(1==n, 0, (1/2)*(2 + ((omega(n)+bigomega(n))^2) - omega(n) - 3*bigomega(n)));
(Scheme) (define (A289621 n) (if (= 1 n) 0 (* (/ 1 2) (+ (expt (+ (A001221 n) (A001222 n)) 2) (- (A001221 n)) (- (* 3 (A001222 n))) 2))))
CROSSREFS
Cf. A001221, A001222, A008966, A046660, A070012, A070013, A070014, A088529, A088530, A181591 (sequences with matching equivalence classes).
Sequence in context: A377801 A369038 A161686 * A069626 A348495 A249274
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 16 2017
STATUS
approved