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A048121
a(n) = (1/2)*T(2n,n+1), where T is given by A048113.
0
0, 0, 1, 3, 12, 42, 156, 570, 2124, 7926, 29844, 112812, 428712, 1635108, 6259236, 24031260, 92517180, 357019224, 1380671532, 5349496152, 20762603724, 80709201504, 314178212928, 1224576411084, 4778651920092, 18667769062044
OFFSET
1,4
CROSSREFS
Cf. A048113.
Sequence in context: A067819 A094970 A065179 * A191112 A066987 A366617
KEYWORD
nonn
STATUS
approved