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 A215675 a(1) = 1, a(n) = 2 if 1
 1, 2, 2, 4, 3, 5, 3, 7, 5, 8, 4, 9, 6, 9, 4, 11, 8, 13, 6, 14, 9, 13, 5, 14, 10, 16, 7, 16, 10, 14, 5, 16, 12, 20, 9, 22, 14, 20, 7, 21, 15, 24, 10, 23, 14, 19, 6, 20, 15, 25, 11, 27, 17, 24, 8, 24, 17, 27, 11, 25, 15, 20, 6, 22, 17, 29, 13, 33, 21, 30, 10 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS In the S.-H. Cha reference this is function ~fog_2(n). LINKS Alois P. Heinz, Table of n, a(n) for n = 1..8192 S.-H. Cha, On Parity based Divide and Conquer Recursive Functions, International Conference on Computer Science and Applications, San Francisco, USA, 24-26 October 2012. FORMULA G.f. A(x) satisfies: A(x) = x/(1 - x) + (1 + x + x^2) * A(x^2). - Ilya Gutkovskiy, May 23 2020 MAPLE a:= proc(n) option remember; 1+ `if`(n=1, 0, `if`(n<=3, 1,       `if`(irem(n-1, 2, 'r')=0, a(r), a(r)+a(r+1))))     end: seq (a(n), n=1..80);  # Alois P. Heinz, Aug 23 2012 MATHEMATICA a[n_] := a[n] = If[n < 3, n, {q, r} = QuotientRemainder[n, 2];      Switch[r, 1, a[q] + 1, 0, a[q-1] + a[q] + 1]]; Table[a[n], {n, 1, 80}] (* Jean-François Alcover, Apr 24 2022 *) CROSSREFS Cf. A215673, A215674, A215676. Sequence in context: A269502 A054346 A145393 * A329439 A132802 A341947 Adjacent sequences:  A215672 A215673 A215674 * A215676 A215677 A215678 KEYWORD nonn AUTHOR Sung-Hyuk Cha, Aug 20 2012 STATUS approved

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Last modified July 7 02:44 EDT 2022. Contains 355141 sequences. (Running on oeis4.)