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A199123 Number of partitions of n into distinct terms of (2,3)-Ulam sequence, cf. A001857. 6

%I

%S 1,0,1,1,0,2,0,2,2,2,3,2,3,3,4,4,5,5,6,6,6,8,8,9,11,10,12,14,12,17,16,

%T 17,22,19,24,25,25,30,30,33,37,37,42,45,46,52,54,57,64,66,69,79,76,87,

%U 93,91,109,105,115,126,123,140,144,151,166,169,180,193

%N Number of partitions of n into distinct terms of (2,3)-Ulam sequence, cf. A001857.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/UlamSequence.html">Ulam Sequence</a>

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Ulam_number">Ulam number</a>

%H <a href="/index/U#Ulam_num">Index entries for Ulam numbers</a>

%e The first terms of A001857 are 2, 3, 5, 7, 8, 9, 13, 14, 18, 19, 24, ...

%e a(20) = #{18+2, 13+7, 13+5+2, 9+8+3, 8+7+5, 8+7+3+2} = 6;

%e a(21) = #{19+2, 18+3, 14+7, 14+5+2, 13+8, 13+5+3, 9+7+5, 9+7+3+2} = 8.

%o (Haskell)

%o a199123 = p a001857_list where

%o p _ 0 = 1

%o p (u:us) m | m < u = 0

%o | otherwise = p us (m - u) + p us m

%Y Cf. A000586; A199122, A199017, A199119, A199121.

%K nonn

%O 0,6

%A _Reinhard Zumkeller_, Nov 03 2011

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Last modified July 11 23:53 EDT 2020. Contains 335654 sequences. (Running on oeis4.)