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The number of distinct parts in the partition sequence lambda(n) formed by the recurrence lambda(1) = 1 and lambda(n+1) is the sum of lambda(n) and its conjugate.
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%I #7 Jul 24 2014 06:28:48

%S 1,1,2,3,4,6,8,11,15,22,30,39,53,75,106,151,215,297,424,592,835,1162,

%T 1618,2274,3217,4556,6361,8940,12560,17645,24822,34812,48967,68861,

%U 96939,136462,191896,269976,379726,534239,751829,1058170,1489038,2096243,2951262

%N The number of distinct parts in the partition sequence lambda(n) formed by the recurrence lambda(1) = 1 and lambda(n+1) is the sum of lambda(n) and its conjugate.

%C lambda(n) is a partition of 2^(n-1).

%C The largest part of lambda(n) is A000045(n).

%C The number of parts of lambda(n) is A000045(n+1). _Peter J. Taylor_, Jul 24 2014

%e lambda(4) = 3+2+1+1+1 has conjugate partition 5+2+1, so lambda(5) = 5+3+2+2+1+1+1+1 and a(5) = |{5,3,2,1}| = 4.

%Y Cf. A000700, A000701, A000045.

%K nonn

%O 1,3

%A _Naohiro Nomoto_, Feb 14 2002

%E More terms, description and example rephrased by _Peter J. Taylor_, Jul 24 2014