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A323111
Number of compositions of 2n where the difference between largest and smallest parts equals n.
3
0, 2, 3, 12, 23, 61, 135, 306, 679, 1499, 3257, 7053, 15167, 32443, 69080, 146533, 309743, 652762, 1371897, 2876284, 6017100, 12562511, 26180328, 54469099, 113151406, 234723068, 486276265, 1006195365, 2079647131, 4293758081, 8856361762, 18250277543
OFFSET
1,2
LINKS
FORMULA
a(n) = A214258(2n,n).
Conjecture: a(n) ~ n * 2^(n-3). - Vaclav Kotesovec, Jan 07 2019
EXAMPLE
a(2) = 2: 13, 31.
a(3) = 3: 114, 141, 411.
a(4) = 12: 1115, 1151, 1511, 5111, 125, 152, 215, 251, 512, 521, 26, 62.
a(5) = 23: 11116, 11161, 11611, 16111, 61111, 1126, 1162, 1216, 1261, 1612, 1621, 2116, 2161, 2611, 6112, 6121, 6211, 136, 163, 316, 361, 613, 631.
CROSSREFS
Cf. A117989 (the same for partitions), A214258.
Sequence in context: A323125 A323126 A323127 * A302545 A320173 A107928
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jan 04 2019
STATUS
approved