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A199770 Self-convolution with "addition" played by bitwise XOR. 4
1, 0, 2, 6, 18, 50, 146, 426, 1282, 3810, 11394, 34082, 102338, 306658, 919874, 2759154, 8276898, 24828386, 74484386, 223444258, 670326242, 2010964770, 6032902242, 18098635298, 54295809826, 162887261410, 488661978274, 1465985458850, 4397955924386 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

FORMULA

a(1)=1, a(n) = sum ( a(i) XOR a(n-i), i = 1 .. n-1).

MAPLE

a:= proc(n) option remember; `if`(n=0, 1, add(

      Bits[Xor](a(i), a(n-1-i)), i=0..n-1))

    end:

seq(a(n), n=0..35);  # Alois P. Heinz, Jun 16 2018

MATHEMATICA

a[1] = 1; a[n_] := a[n] = Sum[BitXor[a[i], a[n - i]], {i, 1, n - 1}]; Table[a[n], {n, 30}]

PROG

(Haskell)

import Data.Bits (xor)

a199770 n = a199770_list !! (n-1)

a199770_list = 1 : f [1] where

   f xs = y : f (y : xs) where

     y = sum $ zipWith xor xs $ reverse xs :: Integer

-- Reinhard Zumkeller, Jul 15 2012

CROSSREFS

Cf. A000108 (Catalan numbers).

Cf. A007462, A192484.

Sequence in context: A081154 A002900 A309087 * A204322 A196593 A248735

Adjacent sequences:  A199767 A199768 A199769 * A199771 A199772 A199773

KEYWORD

nonn,easy

AUTHOR

Jacob A. Siehler, Nov 10 2011

STATUS

approved

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Last modified January 22 06:03 EST 2021. Contains 340360 sequences. (Running on oeis4.)