A336433 - OEIS

%I #29 May 24 2021 00:08:44

%S 0,0,0,1,5,68,403,7257,61686,1174434,13810620,335547727,3783688286,

%T 124486381056,1935430229612,55798127869680,1058567311736669,

%U 39819079382937334,717447490866241055,32064848897165970340,666062878027691348450,28916070816360797805534

%N Number of sequences of n numbers from 1 to n that do not have a subsequence that adds up to n.

%C The sequence is bounded above for odd n by (((n-1)/2)^n)*(2^((n-1)/2)).

%C Growth appears to be slightly faster than exponential, but irregular, with odd-numbered terms larger than the trend.

%H Christopher L. Reedy, <a href="/A336433/b336433.txt">Table of n, a(n) for n = 1..30</a>

%H Pierre Abbat, <a href="https://github.com/phma/fullproc">Fullproc</a>

%H Christopher L. Reedy, <a href="https://github.com/chrisreedy/fun/tree/master/A336433">sequence.py</a>

%e For n=3, the only solution is 2,2,2.

%e For n=4, the 5 solutions are 3,3,3,3 and the four permutations of 3,3,3,2.

%o (C++) See Fullproc link.

%o (Python) # See sequence.py link.

%Y Cf. A000312.

%K nonn

%O 0,5

%A _Pierre Abbat_, Jul 21 2020

%E a(19)-a(21) from _Christopher L. Reedy_, Aug 06 2020