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A101031
Triangle read by rows: T(n,k) = (1/k) times the number of functions from an n-element set into but not onto a k-element set.
0
0, 0, 1, 0, 1, 7, 0, 1, 15, 58, 0, 1, 31, 196, 601, 0, 1, 63, 634, 2765, 7656, 0, 1, 127, 1996, 12265, 44136, 116929, 0, 1, 255, 6178, 52925, 248016, 803383, 2092112, 0, 1, 511, 18916, 223801, 1362096, 5432161, 16595776, 43006401, 0, 1, 1023, 57514, 932525
OFFSET
0,6
FORMULA
T(n, k) = (A089072(n, k)-A019538(n, k))/k (where the two sequences are indexed as triangular arrays).
EXAMPLE
T(3,3) = (1/3)*[ #(functions into) - #(functions onto)] = (3^3 - 6)/3 = 7.
CROSSREFS
Sequence in context: A186642 A153626 A297787 * A222063 A156960 A287697
KEYWORD
nonn,tabl
AUTHOR
Clark Kimberling, Nov 26 2004
STATUS
approved