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A266409
a(n) = (A003309(n+2)-1) / 2; numbers n such that 2n+1 is a Ludic number (in A003309).
6
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
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. A266350 (least monotonic left inverse).
Cf. permutations A266418, A266638.
Cf. also A005097.
Sequence in context: A028767 A268226 A138529 * A035057 A005099 A161720
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jan 28 2016
STATUS
approved