A287292 - OEIS

A287292

a(1) = 1, a(2) = 2; a(n) = a(n-a(n-1)+1) + a(n-a(n-2)-1) for n > 2.

1, 2, 3, 3, 4, 5, 5, 5, 7, 6, 8, 8, 8, 9, 10, 10, 10, 12, 10, 13, 13, 11, 15, 14, 15, 16, 16, 16, 17, 17, 18, 19, 19, 19, 20, 20, 22, 20, 23, 22, 23, 23, 23, 24, 24, 28, 24, 25, 29, 25, 29, 30, 29, 31, 30, 30, 32, 32, 32, 33, 33, 33, 35, 34, 36, 36, 36, 37, 38, 38, 38, 39

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Altug Alkan,Table of n, a(n) for n = 1..10000

Altug Alkan,Plot of a(n)-n/2

Index entries for Hofstadter-type sequences

MATHEMATICA

a[n_]:= a[n] = If[n <= 2, n, a[n - a[n - 1] + 1] + a[n - a[n - 2] - 1]]; Array[a, 72] (*Michael De Vlieger,May 22 2017 *)

PROG

(PARI) q=vector(10000); q[1]=1; q[2]=2; for(n=3, #q, q[n]=q[n-q[n-1]+1]+q[n-q[n-2]-1]); vector(10000, n, q[n])

(Scheme)

;; An implementation of memoization-macro definec can be found for example in: http://oeis.org/wiki/Memoization

(definec (A287292n) (if (<= n 2) n (+ (A287292(+ 1 (- n (A287292(- n 1))))) (A287292(+ -1 (- n (A287292(- n 2))))))));;Antti Karttunen,May 30 2017

CROSSREFS

Cf.A005185.

Sequence in context:A073092 A088023 A324477*A260717 A282719 A061451

Adjacent sequences:A287289 A287290 A287291*A287293 A287294 A287295

KEYWORD

nonn

AUTHOR

Altug Alkan,May 22 2017

STATUS

approved