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A293176
Irregular triangle read by rows: T(n,k) = number of numerical semigroups of genus n with k even gaps.
0
1, 1, 1, 1, 1, 2, 1, 1, 2, 4, 1, 2, 6, 3, 1, 2, 7, 12, 1, 1, 2, 7, 19, 10, 1, 2, 7, 21, 32, 4, 1, 2, 7, 23, 51, 33, 1, 1, 2, 7, 23, 62, 91, 18, 1, 2, 7, 23, 65, 142, 98, 5, 1, 2, 7, 23, 68, 174, 257, 59, 1, 1, 2, 7, 23, 68, 192, 412, 271, 25, 1, 2, 7, 23, 68, 197, 514, 678, 197, 6
OFFSET
0,6
LINKS
M. Bernardini, Fernando Torres. "Counting numerical semigroups by genus and even gaps." Discrete Mathematics 340.12 (2017): 2853-2863. Also arXiv:1612.01212.
EXAMPLE
Triangle begins:
1,
1,
1,1,
1,2,1,
1,2,4,
1,2,6,3,
1,2,7,12,1,
1,2,7,19,10,
1,2,7,21,32,4,
1,2,7,23,51,33,1,
1,2,7,23,62,91,18,
1,2,7,23,65,142,98,5,
1,2,7,23,68,174,257,59,1,
1,2,7,23,68,192,412,271,25,
1,2,7,23,68,197,514,678,197,6,
...
CROSSREFS
Cf. A007323 (row sums).
Sequence in context: A056061 A029265 A103648 * A297170 A359627 A127309
KEYWORD
nonn,tabf
AUTHOR
N. J. A. Sloane, Oct 19 2017
STATUS
approved