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A363511
Number of partitions of [n] having exactly one parity change within their blocks.
2
0, 0, 1, 2, 6, 18, 61, 210, 778, 3008, 12219, 52268, 231726, 1083012, 5202199, 26307710, 135972580, 738339310, 4081523615, 23649300862, 139096468520, 855529383396, 5329630673249, 34643027568520, 227682351175868, 1558106351450416, 10766192988109009
OFFSET
0,4
LINKS
EXAMPLE
a(4) = 6: 124|3, 12|3|4, 134|2, 1|23|4, 14|2|3, 1|2|34.
MAPLE
b:= proc(n, x, y) option remember; convert(series(
`if`(n=0, 1, `if`(y=0, 0, expand(b(n-1, y-1, x+1)*y*z))
+b(n-1, y, x)*x + b(n-1, y, x+1)), z, 2), polynom)
end:
a:= n-> coeff(b(n, 0$2), z, 1):
seq(a(n), n=0..27);
CROSSREFS
Column k=1 of A363493.
Sequence in context: A357693 A150047 A150048 * A150049 A150050 A192318
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jun 06 2023
STATUS
approved