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A102765
Array read by antidiagonals: T(n, k) = ((n+4)^k-(n-1)^k)/5.
0
0, 0, 1, 0, 1, 3, 0, 1, 5, 13, 0, 1, 7, 25, 51, 0, 1, 9, 43, 125, 205, 0, 1, 11, 67, 259, 625, 819, 0, 1, 13, 97, 477, 1555, 3125, 3277, 0, 1, 15, 133, 803, 3355, 9331, 15625, 13107, 0, 1, 17, 175, 1261, 6505, 23517, 55987, 78125, 52429, 0, 1, 19, 223, 1875, 11605
OFFSET
0,6
COMMENTS
Consider a 5x5 matrix M =
[n, 1, 1, 1, 1]
[1, n, 1, 1, 1]
[1, 1, n, 1, 1]
[1, 1, 1, n, 1]
[1, 1, 1, 1, n].
The n-th row of the array contains the values of the non diagonal elements of M^k, k=0,1,.... (Corresponding diagonal entry = non diagonal entry + (n-1)^k.)
For row r we have polynomial ((r+4)^n-(r-1)^n)/5. Corresponding g.f.s: x/((1-(r-1)x)(1-(r+4)x))
If r(n) denotes a row sequence, r(n+1)/r(n) converges to n+4.
Triangle T(n, k) = (4^(n-k-1)-(-1)^(n-k-1))/5*(binomial(k+(n-k-1),n-k-1)) gives coefficients for polynomials for the columns of the array. First four polynomial are:
1
3 + 2*k
13 + 9*k + 3*k^2
51 + 52*k + 18*k^2 + 4*k^3
...
EXAMPLE
Array begins:
0, 1, 3, 13, 51, 205, ...
0, 1, 5, 25, 125, 625, ...
0, 1, 7, 43, 259, 1555, ...
0, 1, 9, 67, 477, 3355, ...
0, 1, 11, 97, 803, 6505, ...
...
PROG
(PARI) MM(n, N)=local(M); M=matrix(n, n); for(i=1, n, for(j=1, n, if(i==j, M[i, j]=N, M[i, j]=1))); M
for(k=0, 10, for(i=0, 10, print1((MM(5, k)^i)[1, 2], ", ")); print())
(PARI) p(n, k)=((n+4)^k-(n-1)^k)/5
for(k=0, 10, for(i=0, 10, print1(p(k, i), ", ")); print())
(PARI) for(k=0, 10, for(i=0, 10, print1(polcoeff(x/((1-(k-1)*x)*(1-(k+4)*x)), i), ", ")); print())
CROSSREFS
Cf. A015521 (for n=0), A000351 (for n=1), A003464 (for n=2), A016130 (for n=3), A016140 (for n=4), A016153 (for n=5), A016164 (for n=6), A016174 (for n=7), A016184 (for n=8), A015441 (for n=-1), A091005 (for n=-2).
Sequence in context: A119925 A210663 A355172 * A355257 A129684 A247255
KEYWORD
nonn,tabl
AUTHOR
Lambert Klasen (lambert.klasen(AT)gmx.net) and Gary W. Adamson, Feb 10 2005
STATUS
approved