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

0,5

Comments

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

Links

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

Example

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.

Prog

(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_vec<n & A064657_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

Crossrefs

Sequence in context: A377672 A009664 A009507 * A182837 A256940 A361833

Adjacent sequences: A064654 A064655 A064656 * A064658 A064659 A064660

Keyword

nonn,fini,full

Author

Roger L. Bagula, Oct 08 2001

Extensions

More terms from Vladeta Jovovic, Oct 09, 2001

Keyword fini added by Reinhard Zumkeller, Jul 21 2012

Status

approved