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A049017 Expansion of 1/((1-x)^7-x^7). 3
1, 7, 28, 84, 210, 462, 924, 1717, 3017, 5110, 8568, 14756, 27132, 54264, 116281, 257775, 572264, 1246784, 2641366, 5430530, 10861060, 21242341, 40927033, 78354346, 150402700, 291693136, 574274008, 1148548016, 2326683921, 4749439975, 9714753412, 19818498700, 40199107690 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Differs for n >= 7 (1717 vs. 1716) from A000579(n+6) = binomial(n+6,6); see also row 6 of A027555, A059481 and A213808. - M. F. Hasler, Mar 05 2017

LINKS

Table of n, a(n) for n=0..32.

Index entries for linear recurrences with constant coefficients, signature (7,-21,35,-35,21,-7,2).

FORMULA

G.f.: 1/((1-x)^7 - x^7) = 1/(1 - 7x + 21x^2 - 35x^3 + 35x^4 - 21x^5 + 7x^6 - 2x^7).

MATHEMATICA

CoefficientList[Series[1/((1-x)^7-x^7), {x, 0, 30}], x]  (* Harvey P. Dale, Feb 18 2011 *)

PROG

(PARI) Vec(1/((1-x)^7-x^7)+O(x^99)) \\ M. F. Hasler, Mar 05 2017

CROSSREFS

Cf. A000750, A049016, A049018.

Sequence in context: A278969 A000579 A290994 * A019501 A229887 A243741

Adjacent sequences:  A049014 A049015 A049016 * A049018 A049019 A049020

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified October 16 13:12 EDT 2018. Contains 316263 sequences. (Running on oeis4.)