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

2, 5, 16, 12, 67, 9, 16, 23, 436, 80, 1771, 18, 67, 80, 1771, 668, 16111, 48, 277, 302, 7141, 2630, 64621, 14, 16, 23, 436, 80, 1771, 31, 436, 467, 21946, 1832, 87991, 94, 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

Offset: 1

Author

Antti Karttunen, May 08 2017

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10080
• Eric Weisstein's World of Mathematics, Pairing Function
• Index entries for sequences related to factorial base representation

Crossrefs

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

Programs

Scheme

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

Formula

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