A001717 Generalized Stirling numbers.

1, 15, 179, 2070, 24574, 305956, 4028156, 56231712, 832391136, 13051234944, 216374987520, 3785626465920, 69751622298240, 1350747863435520, 27437426560500480, 583506719443584000, 12969079056388224000, 300749419818102528000, 7265204785551331584000

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Comments

The asymptotic expansion of the higher order exponential integral E(x,m=3,n=4) ~ exp(-x)/x^3*(1 - 15/x + 179/x^2 - 2070/x^3 + 24574/x^4 - 305956/x^5 + ...) leads to the sequence given above. See A163931 and A163932 for more information. - Johannes W. Meijer, Oct 20 2009

From Petros Hadjicostas, Jun 25 2020: (Start)

For nonnegative integers n, m and complex numbers a, b (with b <> 0), the numbers R_n^m(a,b) were introduced by Mitrinovic (1961) and Mitrinovic and Mitrinovic (1962) using slightly different notation.

These numbers are defined via the g.f. Product_{r=0..n-1} (x - (a + b*r)) = Sum_{m=0..n} R_n^m(a,b)*x^m for n >= 0.

As a result, R_n^m(a,b) = R_{n-1}^{m-1}(a,b) - (a + b*(n-1))*R_{n-1}^m(a,b) for n >= m >= 1 with R_0^0(a,b) = 1, R_1^0(a,b) = a, R_1^1(a,b) = 1, and R_n^m(a,b) = 0 for n < m.

We have R_n^m(a,b) = Sum_{k=0}^{n-m} (-1)^k * a^k * b^(n-m-k) * binomial(m+k, k) * S1(n, m+k) for n >= m >= 0.

For the current sequence, a(n) = R_{n+2}^2(a=-4, b=-1) for n >= 0. (End)

References

• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• T. D. Noe, Table of n, a(n) for n = 0..100
• D. S. Mitrinovic, Sur une classe de nombres reliés aux nombres de Stirling, Comptes rendus de l'Académie des sciences de Paris, t. 252 (1961), 2354-2356. [The numbers R_n^m(a,b) are introduced.]
• D. S. Mitrinovic and R. S. Mitrinovic, Tableaux d'une classe de nombres reliés aux nombres de Stirling, Univ. Beograd. Publ. Elektrotehn. Fak. Ser. Mat. Fiz., No. 77 (1962), 1-77 [jstor stable version].
• D. S. Mitrinovic and M. S. Mitrinovic, Tableaux d'une classe de nombres reliés aux nombres de Stirling, Univ. Beograd. Publ. Elektrotehn. Fak. Ser. Mat. Fiz. No. 77 (1962), 1-77.

Programs

Mathematica

nn = 20; t = Range[0, nn]! CoefficientList[Series[(1 - 9*Log[1 - x] + 10*Log[1 - x]^2)/(1 - x)^6, {x, 0, nn}], x] (* T. D. Noe, Aug 09 2012 *)

PARI

a(n) = sum(k=0, n, (-1)^(n+k)*binomial(k+2, 2)*4^k*stirling(n+2, k+2, 1)); \\ Michel Marcus, Jan 20 2016

Formula

a(n) = Sum_{k=0..n} (-1)^(n+k) * binomial(k+2, 2) * 4^k * Stirling1(n+2, k+2). - Borislav Crstici (bcrstici(AT)etv.utt.ro), Jan 26 2004

E.g.f.: (1 - 9*log(1 - x) + 10*log(1 - x)^2)/(1 - x)^6. - Vladeta Jovovic, Mar 01 2004

If we define f(n,i,a) = Sum_{k=0..n-i} binomial(n,k) * Stirling1(n-k,i) * Product_{j=0..k-1} (-a-j), then a(n-2) = |f(n,2,4)| for n>=2. - Milan Janjic, Dec 21 2008

From Petros Hadjicostas, Jun 26 2020: (Start)

a(n) = [x^2] Product_{r=0..n+1} (x + 4 + r) = (Product_{r=0..n+1} (4 + r)) * Sum_{0 <= i < j <= n+1} 1/((4 + i)*(4 + j)).

Since a(n) = R_{n+2}^2(a=-4, b=-1) and R_n^m(a,b) = R_{n-1}^{m-1}(a,b) - (a + b*(n-1))*R_{n-1}^m(a,b), we conclude that:

(i) a(n) = A001716(n) + (n+5)*a(n-1) for n >= 1;

(ii) a(n) = (n+3)!/6 + (2*n+9)*a(n-1) - (n+4)^2*a(n-2) for n >= 2.

(iii) a(n) = 3*(n+4)*a(n-1) - (3*n^2+21*n+37)*a(n-2) + (n+3)^3*a(n-3) for n >= 3. (End)

Extensions

More terms from Borislav Crstici (bcrstici(AT)etv.utt.ro), Jan 26 2004