A064657 a(n) = a(|n - a(n-3)|) + a(|n - a(n-4)|) for n > 3, a(n)=1 otherwise.

1, 1, 1, 1, 2, 4, 8, 12, 10, 5, 2, 2, 13, 12, 26, 13, 3, 9, 14, 11, 11, 25, 12, 26, 13, 13, 27, 27, 26, 4, 2, 6, 34, 10, 60, 5, 28, 53, 22, 62, 25, 24, 22, 25, 22, 51, 38, 25, 28, 3, 26, 53, 16, 53, 27, 63, 26, 4, 10, 12, 86, 57, 42, 79, 24, 36, 25, 38, 56, 32, 85, 23

Offset: 0

Author

Roger L. Bagula, Oct 08 2001

Keywords

• nonn
• fini
• full

Comments

The sequence is defined only for n <= 866, see example. - Reinhard Zumkeller, Jul 21 2012

Examples

			Last term: a(866) = a(|866 - a(866-3)|) + a(|866 - a(866-4)|) = a(|866 - a(863)|) + a(|866 - a(862)|) = a(|866 - 718|) + a(|866 - 88|) = a(148) + a(778) = 28 + 655 = 683,
but a(867) = a(|867 - a(867-3)|) + a(|867 - a(867-4)|) = a(|867 - a(864)|) + a(|867 - a(863)|) =  a(|867 - 2546|) + a(|867 - 718|) = a(1679) + a(149) = undefined + 112 = undefined.
		

Links

• Reinhard Zumkeller, full Table of n, a(n) for n = 0..866

Programs

Haskell

a064657 n = a064657_list !! n
a064657_list = map fromJust $ takeWhile (/= Nothing) zs where
  z n = fromJust $ zs !! n
  zs = (map Just [1,1,1,1]) ++ f 4 where
     f x = y : f (x + 1) where
       y | 2*x < max i3 i4 = Nothing
         | otherwise       = Just $ z (abs (x - i3)) + z (abs (x - i4))
         where i3 = z (x - 3); i4 = z (x - 4)
b064657 = bFile' "A064657" a064657_list 0 -- (0.03 secs, 3184228 bytes)
-- Reinhard Zumkeller, Jul 21 2012

PARI

A064657_vec=[1,1,1]; A064657(n)={n<4 & return(1);
#A064657_vecA064657_vec=concat(A064657_vec, vector(n-#A064657_vec)); A064657_vec[n] & return(A064657_vec[n]); A064657_vec[n]=A064657(abs(A064657(n-3)-n))+A064657(abs(A064657(n-4)-n))} \\ - M. F. Hasler, Aug 28 2012

Extensions

More terms from Vladeta Jovovic, Oct 09 2001

Keyword fini added by Reinhard Zumkeller, Jul 21 2012