A266409 a(n) = (A003309(n+2)-1) / 2; numbers n such that 2n+1 is a Ludic number (in A003309).

1, 2, 3, 5, 6, 8, 11, 12, 14, 18, 20, 21, 23, 26, 30, 33, 35, 38, 41, 44, 45, 48, 53, 57, 59, 60, 63, 65, 71, 74, 78, 80, 86, 87, 89, 90, 96, 104, 105, 110, 111, 113, 116, 117, 119, 123, 128, 132, 138, 141, 143, 150, 153, 156, 164, 165, 168, 170, 176, 179, 180, 188, 191, 194, 198, 203, 207, 209, 210, 215

Offset

1,2

Comments

Ludic numbers from A003309(2) = 3 onward, decremented by one, then halved.

Links

Antti Karttunen, Table of n, a(n) for n = 1..10226

Formula

a(n) = (A003309(n+2)-1) / 2.

Other identities. For all n >= 1:

A266350(a(n)) = n.

Prog

(Scheme, two versions)
(define (A266409 n) (/ (- (A003309 (+ 2 n)) 1) 2))
(define A266409 (NONZERO-POS 1 1 (lambda (n) (A192490 (+ n n 1))))) ;; Requires Antti Karttunen's IntSeq-library,

Crossrefs

Complement: A266410.

Cf. A003309, A192490.

Cf. A266350 (least monotonic left inverse).

Cf. permutations A266418, A266638.

Cf. also A005097.

Sequence in context: A028767 A268226 A138529 * A035057 A005099 A161720

Adjacent sequences: A266406 A266407 A266408 * A266410 A266411 A266412

Keyword

nonn

Author

Antti Karttunen, Jan 28 2016

Status

approved