cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A281588 E.g.f. z*(2*(exp(z) + 1)/(cosh(z) + cos(z)) - 1).

Original entry on oeis.org

0, 1, 2, 3, 4, -5, -24, -98, -272, 621, 4960, 31856, 132672, -437593, -4893056, -42854160, -237969664, 1026405753, 14756156928, 163699919104, 1136284574720, -6054175060941, -106379840985088, -1428593836836352, -11899498670002176, 75477454065058725
Offset: 0

Views

Author

Peter Luschny, Feb 01 2017

Keywords

Crossrefs

Cf. A281587.

Programs

  • Maple
    A281588_list := proc(n) z*(2*(exp(z)+1)/(cosh(z)+cos(z))-1);
    series(%,z,n+1); seq(k!*coeff(%,z,k),k=0..n) end: A281588_list(25);
  • Sage
    def SIB(dim, m): # Algorithm of L. Seidel (1877).
        E = matrix(ZZ, dim)
        def plow(n, dir):
            if dir : # right to left backward
                E[n, 0] = int(n == 1)
                for k in range(n-1, -1, -1) :
                    E[k, n-k] = E[k+1, n-k-1] - E[k, n-k-1]
            else:  # left to right forward
                E[0, n] = 0
                for k in range(1, n+1, 1) :
                    E[k, n-k] = E[k-1, n-k+1] + E[k-1, n-k]
        dir = [mod(n, m) == 1 for n in (0..dim-1)]
        for n in (0..dim-1): plow(n, dir[n])
        return [E[0,k] if dir[k] else E[k,0] for k in range(dim)]
    A281588_list = lambda len: SIB(len, 4)
    A281588_list(26)
Showing 1-1 of 1 results.