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A056615
Binomial(2*n - 1, n - 1) - 1 (mod n^2).
0
0, 2, 0, 2, 0, 29, 0, 34, 9, 77, 0, 61, 0, 51, 134, 34, 0, 137, 0, 9, 401, 123, 0, 269, 125, 171, 252, 475, 0, 811, 0, 290, 977, 869, 615, 673, 0, 363, 9, 409, 0, 755, 0, 1123, 1259, 531, 0, 1421, 1715, 1127, 2321, 1555, 0, 1919, 1940, 2171, 1814, 843, 0, 3527, 0, 963
OFFSET
1,2
COMMENTS
a(n) = 0 iff n is an odd prime.
MATHEMATICA
Table[Mod[Binomial[2*n - 1, n - 1] - 1, n^2], {n, 1, 100}]
CROSSREFS
Sequence in context: A137949 A019214 A137668 * A060989 A135298 A006996
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Aug 07 2000
STATUS
approved