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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A370691 Square array read by upward antidiagonals: T(n, k) = denominator( 2*k!*(-2)^k*Sum_{m=1..n}( 1/(2*m-1)^(k+1) ) ).

Original entry on oeis.org

1, 1, 1, 3, 1, 1, 15, 9, 1, 1, 105, 225, 27, 1, 765765, 405810405, 91398648466125, 48049812916875, 1033788065625, 89339709375, 3796875, 729, 1, 1, 1, 315, 11025, 3375, 27, 1, 1, 3465, 99225, 1157625, 16875, 81, 1, 1, 45045, 12006225, 31255875, 40516875, 253125, 243, 1, 1, 45045, 2029052025
Offset: 0

Views

Author

Thomas Scheuerle, Apr 21 2024

Keywords

Examples

			array begins:
1,    1,        1,           1,              1,                  1
1,    1,        1,           1,              1,                  1
3,    9,        27,          27,             81,                 243
15,   225,      3375,        16875,          253125,             759375
105,  11025,    1157625,     40516875,       4254271875,         89339709375
315,  99225,    31255875,    3281866875,     1033788065625,      65128648134375
3465, 12006225, 41601569625, 48049812916875, 166492601756971875, 115379373017581509375
		

Crossrefs

Cf. A370692 (numerators),
Cf. A025547 (first column), A128492 (second column).
Cf. A128507.
Cf. A255008 (denominators polygamma(n, 1) - polygamma(n, k)).
Cf. A255009 (numerators polygamma(n, 1) - polygamma(n, k)).

Programs

  • Maple
    A := (n, k) -> Psi(k, n + 1/2) - Psi(k, 1/2):
    seq(lprint(seq(denom(A(n, k)), k = 0..4)), n=0..6);
  • PARI
    T(n, k) = denominator(sum(m=1, n, 1/(2*m-1)^(k+1))*k!*(-2)^k*2)

Formula

T(n, k) = denominator( polygamma(k, n + 1/2) - polygamma(k, 1/2) ).
T(n, k) = denominator( k!*(-1)^(k+1)*(zeta((k+1), 1/2 + n) - zeta((k+1), 1/2)) ), where zeta is the Hurwitz zeta function.
T(n, 0) = A025547(n).
T(n, 1) = A128492(n).
Conjectured: T(n, 2) = A128507(n).
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