cp's OEIS Frontend

A320556 Number of set partitions of [n] such that for each block b the smallest integer interval containing b has at most six elements and for at least one block c the smallest integer interval containing c has exactly six elements.

%I A320556 #6 Oct 17 2018 17:05:45
%S A320556 52,265,966,3172,10100,32918,111138,373888,1238236,4034221,12991481,
%T A320556 41567855,132719006,423099220,1346053178,4271656023,13520858094,
%U A320556 42696919677,134582517515,423599583268,1331701708711,4182193622677,13121508724973,41131777789545
%N A320556 Number of set partitions of [n] such that for each block b the smallest integer interval containing b has at most six elements and for at least one block c the smallest integer interval containing c has exactly six elements.
%H A320556 Alois P. Heinz, <a href="/A320556/b320556.txt">Table of n, a(n) for n = 6..1000</a>
%F A320556 a(n) = A276722(n) - A276721(n).
%p A320556 b:= proc(n, m, l) option remember; `if`(n=0, 1,
%p A320556       add(b(n-1, max(m, j), [subsop(1=NULL, l)[],
%p A320556       `if`(j<=m, 0, j)]), j={l[], m+1} minus {0}))
%p A320556     end:
%p A320556 A:= (n, k)-> `if`(n=0, 1, `if`(k<2, k, b(n, 0, [0$(k-1)]))):
%p A320556 a:= n-> (k-> A(n, k) -`if`(k=0, 0, A(n, k-1)))(6):
%p A320556 seq(a(n), n=6..50);
%Y A320556 Column k=6 of A276727.
%Y A320556 Cf. A276721, A276722, A320619.
%K A320556 nonn,easy
%O A320556 6,1
%A A320556 _Alois P. Heinz_, Oct 15 2018