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.

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

Links

Antti Karttunen, Table of n, a(n) for n = 1..10000

Index entries for sequences computed from exponents in factorization of n

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. A000027, A046523.

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

Sequence in context: A347957 A369038 A161686 * A069626 A348495 A249274

Adjacent sequences: A289618 A289619 A289620 * A289622 A289623 A289624

Keyword

nonn

Author

Antti Karttunen, Jul 16 2017

Status

approved