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A294933
Compound filter related to base-3 expansion of the exponents in prime factorization of n: a(n) = P(A294932(n), A294931(n)), where P(n,k) is sequence A000027 used as a pairing function.
3
1, 2, 2, 3, 2, 7, 2, 4, 3, 7, 2, 5, 2, 7, 7, 16, 2, 5, 2, 5, 7, 7, 2, 16, 3, 7, 4, 5, 2, 29, 2, 8, 7, 7, 7, 10, 2, 7, 7, 16, 2, 29, 2, 5, 5, 7, 2, 67, 3, 5, 7, 5, 2, 16, 7, 16, 7, 7, 2, 12, 2, 7, 5, 6, 7, 29, 2, 5, 7, 29, 2, 8, 2, 7, 5, 5, 7, 29, 2, 67, 16, 7, 2, 12, 7, 7, 7, 16, 2, 12, 7, 5, 7, 7, 7, 23, 2, 5, 5, 10, 2, 29, 2, 16, 29, 7, 2, 8, 2, 29, 7, 67
OFFSET
1,2
COMMENTS
For all i, j: a(i) = a(j) => A038148(i) = A038148(j).
FORMULA
a(n) = (1/2)*(2 + ((A294932(n) + A294931(n))^2) - A294932(n) - 3*A294931(n)).
PROG
(define (A294933 n) (* 1/2 (+ (expt (+ (A294932 n) (A294931 n)) 2) (- (A294932 n)) (- (* 3 (A294931 n))) 2)))
CROSSREFS
Cf. also A293225, A293226 and A293442 (analogous filter for base-2).
Sequence in context: A144368 A094438 A156098 * A015996 A256564 A092976
KEYWORD
nonn
AUTHOR
Antti Karttunen, Nov 11 2017
STATUS
approved