A286382 Compound filter: a(n) = P(A257993(n), A278226(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, 156, 1129, 1178, 28681, 10442, 258841, 14, 16, 23, 436, 80, 1771, 31, 436, 467, 21946, 1832, 87991, 94, 1771, 1832, 87991, 16292, 793171, 328, 7141, 7262, 352381, 64982, 3173941, 1228, 28681, 28922, 1410361, 259562, 12698281, 25, 67, 80, 1771, 668, 16111

Offset: 1

Author

Antti Karttunen, May 08 2017

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..11550
• Eric Weisstein's World of Mathematics, Pairing Function
• Index entries for sequences related to primorial base

Crossrefs

Cf. A000027, A257993, A278226, A286142.

Differs from A286381 for the first time at n=24, where a(24) = 156 while A286381(24) = 14.

Programs

Scheme

(define (A286382 n) (* (/ 1 2) (+ (expt (+ (A257993 n) (A278226 n)) 2) (- (A257993 n)) (- (* 3 (A278226 n))) 2)))

Formula

a(n) = (1/2)*(2 + ((A257993(n)+A278226(n))^2) - A257993(n) - 3*A278226(n)).