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

1,1

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

Formula

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

Prog

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

Crossrefs

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

Sequence in context: A309115 A248125 A297473 * A286382 A127580 A098048

Adjacent sequences: A286378 A286379 A286380 * A286382 A286383 A286384

Keyword

nonn

Author

Antti Karttunen, May 08 2017

Status

approved