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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A342321 T(n, k) = A343277(n)*[x^k] p(n, x) where p(n, x) = (1/(n+1))*Sum_{k=0..n} (-1)^k*E1(n, k)*x^(n - k) / binomial(n, k), and E1(n, k) are the Eulerian numbers A123125. Triangle read by rows, for 0 <= k <= n.

Original entry on oeis.org

1, 0, 1, 0, -1, 2, 0, 1, -4, 3, 0, -3, 22, -33, 12, 0, 1, -13, 33, -26, 5, 0, -5, 114, -453, 604, -285, 30, 0, 5, -200, 1191, -2416, 1985, -600, 35, 0, -35, 2470, -21465, 62476, -78095, 42930, -8645, 280, 0, 14, -1757, 21912, -88234, 156190, -132351, 51128, -7028, 126
Offset: 0

Views

Author

Peter Luschny, Mar 09 2021

Keywords

Comments

Conjecture: For even n >= 6 p(n, x)/x and for odd n >= 3 p(n, x)/(x^2 - x) is irreducible.

Examples

			Triangle starts:
[n]                T(n, k)                      A343277(n)
----------------------------------------------------------
[0] 1;                                                 [1]
[1] 0,  1;                                             [2]
[2] 0, -1,     2;                                      [6]
[3] 0,  1,    -4,     3;                              [12]
[4] 0, -3,    22,   -33,    12;                       [60]
[5] 0,  1,   -13,    33,   -26,     5;                [30]
[6] 0, -5,   114,  -453,   604,  -285,    30;        [210]
[7] 0,  5,  -200,  1191, -2416,  1985,  -600,  35;   [280]
.
The coefficients of the polynomials p(n, x) = (Sum_{k = 0..n} T(n, k) x^k) / A343277(n) for the first few n:
[0] 1;
[1] 0,   1/2;
[2] 0,  -1/6,    1/3;
[3] 0,  1/12,   -1/3,    1/4;
[4] 0, -1/20,   11/30, -11/20,    1/5;
[5] 0,  1/30,  -13/30,  11/10,  -13/15,  1/6.
		

Crossrefs

Sequences of rational polynomials p(n, x) with p(n, 1) = Bernoulli(n, 1):

Programs

  • Maple
    CoeffList := p -> op(PolynomialTools:-CoefficientList(p,x)):
    E1 := (n, k) -> combinat:-eulerian1(n, k):
    poly := n -> (1/(n+1))*add((-1)^k*E1(n,k)*x^(n-k)/binomial(n,k), k=0..n):
    Trow := n -> denom(poly(n))*CoeffList(poly(n)): seq(Trow(n), n = 0..9);
  • Mathematica
    Poly342321[n_, x_] := If[n == 0, 1, Sum[x^k*k!*Sum[(-1)^(n - j)*StirlingS2[n, j] /((k - j)!(n - j + 1) Binomial[n + 1, j]), {j, 0, k}], {k, 1, n}]];
    Table[A343277[n] CoefficientList[Poly342321[n, x], x][[k+1]], {n, 0, 9}, {k, 0, n}] // Flatten

Formula

An alternative representation of the sequence of rational polynomials is:
p(n, x) = Sum_{k=1..n} x^k*k!*Sum_{j=0..k} (-1)^(n-j)*Stirling2(n, j)/((k - j)!(n - j + 1)*binomial(n + 1, j)) for n >= 1 and p(0, x) = 1.
(Sum_{k = 0..n} T(n, k)) / A343277(n) = Bernoulli(n, 1).

A341759 Primes p such that Euler(p, 1) is an integer multiple of Bernoulli(p + 1, 1).

Original entry on oeis.org

5, 17, 41, 53, 293, 881, 2393, 4373, 5333, 5417, 6173, 7937, 12641, 13121, 14153, 16001, 16253, 18521, 23813, 27701, 37337, 42461, 48761, 50273, 58481, 74897, 82781, 88493, 106433, 113777, 143261, 174761, 195281, 227597, 236681, 249317, 297233, 336041, 341333
Offset: 1

Views

Author

Peter Luschny, Mar 24 2021

Keywords

Comments

Primes p such that p+1 is a term of A014741. - Bill McEachen, Sep 20 2021

Examples

			Euler(17, 1) = 29127*Bernoulli(18, 1).
		

Crossrefs

Programs

  • Mathematica
    Select[Select[Range[200000], IntegerQ[(2*(-1 + 2^#1))/#1] &] - 1, PrimeQ] (* Vaclav Kotesovec, Mar 24 2021 *)
    Select[Prime[Range[30000]],Divisible[EulerE[#,1],BernoulliB[#+1]]&]//Quiet (* Harvey P. Dale, Nov 06 2022 *)
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