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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

LINKS

Table of n, a(n) for n=0..79.

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 A127309 A097853

Adjacent sequences:  A293173 A293174 A293175 * A293177 A293178 A293179

KEYWORD

nonn,tabf

AUTHOR

N. J. A. Sloane, Oct 19 2017

STATUS

approved

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Last modified August 18 01:19 EDT 2019. Contains 326059 sequences. (Running on oeis4.)