|
| |
|
|
A266413
|
|
a(1) = 1, after which each a(n) = A002487(n)-th number selected from those not yet in the sequence.
|
|
3
|
|
|
|
1, 2, 4, 3, 7, 6, 9, 5, 12, 11, 15, 10, 17, 14, 18, 8, 21, 20, 25, 19, 28, 24, 29, 16, 31, 27, 34, 23, 35, 30, 33, 13, 38, 37, 43, 36, 47, 42, 48, 32, 51, 46, 55, 41, 56, 49, 53, 26, 57, 52, 62, 45, 65, 59, 64, 40, 66, 60, 69, 50, 68, 58, 63, 22, 71, 70, 77, 67, 82, 76, 83, 61, 87, 81, 92, 75, 93, 84, 89, 54, 94, 88, 101, 80
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
LINKS
|
|
|
|
MATHEMATICA
|
f[n_] := Block[{a = {1}, g, b = Range[2, n]}, g[1] = 1; g[x_] := g[x] = If[EvenQ@ x, g[x/2], g[(x - 1)/2] + g[(x + 1)/2]]; Do[{AppendTo[a, #[[1, 1]]], Set[b, Last@ #]} &@ If[# > Length@ b, Break[], TakeDrop[b, {#}]] &@ g@ k, {k, 2, n}]; a]; f@ 103 (* Michael De Vlieger, Dec 29 2015, Version 10.2, after N. J. A. Sloane at A002487 *)
|
|
|
PROG
|
(Scheme, with defineperm1-macro from Antti Karttunen's IntSeq-library)
(defineperm1 (A266413 n) (if (<= n 1) n (let loop ((i 1) (the-nth-one (+ -1 (A002487 n)))) (cond ((not-lte? (A266414 i) n) (if (zero? the-nth-one) i (loop (+ i 1) (- the-nth-one 1)))) (else (loop (+ i 1) the-nth-one))))))
(define (A266414 n) (A266413 (- n))) ;; This returns inverse values of A266413 from its hidden cache that defineperm1-macro has prepared. #f is returned for those n that have not yet been encountered.
;; We consider a > b (i.e. not less than b) also in case a is #f.
;; (Because of the stateful caching system used by defineperm1-macro):
(define (not-lte? a b) (cond ((not (number? a)) #t) (else (> a b))))
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
