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 A257740 Number T(n,k) of multisets of nonempty words with a total of n letters over k-ary alphabet such that all k letters occur at least once in the multiset; triangle T(n,k), n>=0, 0<=k<=n, read by rows. 16
 1, 0, 1, 0, 2, 3, 0, 3, 14, 13, 0, 5, 49, 114, 73, 0, 7, 148, 672, 1028, 501, 0, 11, 427, 3334, 9182, 10310, 4051, 0, 15, 1170, 15030, 66584, 129485, 114402, 37633, 0, 22, 3150, 63978, 428653, 1285815, 1918083, 1394414, 394353, 0, 30, 8288, 261880, 2557972, 11117600, 24917060, 30044014, 18536744, 4596553 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS Row n is the inverse binomial transform of the n-th row of array A144074, which has the Euler transform of the powers of k in column k. LINKS Alois P. Heinz, Rows n = 0..140, flattened FORMULA T(n,k) = Sum_{i=0..k} (-1)^i * C(k,i) * A144074(n,k-i). EXAMPLE T(2,2) = 3: {ab}, {ba}, {a,b}. T(3,2) = 14: {aab}, {aba}, {abb}, {baa}, {bab}, {bba}, {a,ab}, {a,ba}, {a,bb}, {aa,b}, {ab,b}, {b,ba}, {a,a,b}, {a,b,b}. Triangle T(n,k) begins:   1;   0,  1;   0,  2,    3;   0,  3,   14,    13;   0,  5,   49,   114,     73;   0,  7,  148,   672,   1028,     501;   0, 11,  427,  3334,   9182,   10310,    4051;   0, 15, 1170, 15030,  66584,  129485,  114402,   37633;   0, 22, 3150, 63978, 428653, 1285815, 1918083, 1394414, 394353; MAPLE A:= proc(n, k) option remember; `if`(n=0, 1, add(add(       d*k^d, d=numtheory[divisors](j)) *A(n-j, k), j=1..n)/n)     end: T:= (n, k)-> add(A(n, k-i)*(-1)^i*binomial(k, i), i=0..k): seq(seq(T(n, k), k=0..n), n=0..10); MATHEMATICA A[n_, k_] := A[n, k] = If[n == 0, 1, Sum[DivisorSum[j, #*k^#&]*A[n - j, k], {j, 1, n}]/n]; T[n_, k_] := Sum[A[n, k - i]*(-1)^i*Binomial[k, i], {i, 0, k}]; Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Jan 23 2017, adapted from Maple *) CROSSREFS Columns k=0-10 give: A000007, A000041 (for n>0), A261043, A320213, A320214, A320215, A320216, A320217, A320218, A320219, A320220. Row sums give A257741. Main diagonal gives A000262. T(2n,n) gives A257742. Cf. A144074, A319501. Sequence in context: A253283 A261719 A137663 * A161628 A244119 A122059 Adjacent sequences:  A257737 A257738 A257739 * A257741 A257742 A257743 KEYWORD nonn,tabl AUTHOR Alois P. Heinz, May 06 2015 EXTENSIONS Name changed by Alois P. Heinz, Sep 21 2018 STATUS approved

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Last modified October 15 00:04 EDT 2019. Contains 328025 sequences. (Running on oeis4.)