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A104053 Triangle of coefficients in the numerators of rational functions in tanh(1) that express the (2n)th Du Bois-Reymond constants as C_0 = 0, C_2 = -4 - 1/(1-tanh(1)), for n>1, C_2n = -3 - (Sum_{k=0..n} a(n,k)*tanh(1)^k) / (2^n*n! * (1-tanh(1))^n). 0
0, 1, 0, 1, -1, -1, -1, 0, 0, 3, 1, -5, 18, -13, -7, -11, 70, -135, 65, -10, 45, 111, -609, 1215, -1350, 1275, -621, -141, -1009, 6188, -16758, 27335, -26845, 12474, -2548, 1883, 10977, -81353, 270004, -511791, 584710, -420287, 216468, -70169, -3599, -146691, 1248210, -4715217, 10303461, -14439411 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,10

COMMENTS

For n>0 the row sums = (-1)^(n-1) * (n-1)! For n odd, the sum of the absolute values of the coefficients in the n-th row = (2*(n-1))!/n! (every other entry of A001761).

The sum of the (2n)th Du Bois-Reymond constants = 1/5 or is very close to 1/5.

For the 6th and 9th rows, the coefficients were adjusted from results of the residue evaluations so that double factorials ((2n)!! = 2^n*n! (A000165)) are in the denominators. For the 6th row they were multiplied by 3, for the 9th row they were multiplied by 9.

For n>1, Sum_{k=0..n} (n-k+1)*a(n,k) = (-1)^(n)*A001286(n-1) [A001286 are Lah numbers: (n-1)*n!/2].

LINKS

Table of n, a(n) for n=0..49.

Eric Weisstein. Du Bois Reymond Constants from MathWorld

Eric Weisstein. Double Factorial

FORMULA

For n>1, C_2n = -3 - 2 * Residue_{x=i} (x^2/((1+x^2)^n * (tan(x) - x))) (see MathWorld article).

For n>1, Sum_{k=0..n} (-1)^(n+k)*a(n, k) = (2*(n-1))!/n! (i.e., A001761(n-1)).

MATHEMATICA

Table[2 Residue[x^2/((1+x^2)^n (Tan[x]-x)), {x, I}], {n, 0, 9}]

CROSSREFS

Cf. A000142, A000165, A001761, A062545, A062546, A085466, A085467.

Sequence in context: A124740 A073597 A338172 * A187369 A039512 A140825

Adjacent sequences:  A104050 A104051 A104052 * A104054 A104055 A104056

KEYWORD

hard,sign,tabl

AUTHOR

Gerald McGarvey, Mar 02 2005

EXTENSIONS

Added the keyword tabl Gerald McGarvey, Aug 20 2009

STATUS

approved

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Last modified June 13 11:36 EDT 2021. Contains 344990 sequences. (Running on oeis4.)