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A177187 Union of A057080 and A001090 2
1, 1, 9, 8, 71, 63, 559, 496, 4401, 3905, 34649, 30744, 272791, 242047, 2147679, 1905632, 16908641, 15003009, 133121449, 118118440, 1048062951, 929944511, 8251382159, 7321437648, 64962994321, 57641556673, 511452572409, 453811015736, 4026657584951, 3572846569215 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Column sums of shifted Pascal-like array:

1..1..10..10..100..100.1000.1000

......-1..-2..-30..-40.-500.-600

................1....3...60..100

.........................-1...-4

-------------------------------- +

1..1...9...8...71...63..559..496

Decimal expansion of ratio n/(n+1) is accumulation of Catalan numbers;(5 +/- sqrt(15)).

LINKS

Table of n, a(n) for n=1..30.

Index entries for linear recurrences with constant coefficients, signature (0,8,0,-1).

FORMULA

For n odd a(n) = 10*a(n-1)- a(n-2), for n even a(n) = a(n-1) - a(n-2); with a(0) = 0, a(1) = 1.

G.f. x*(1+x+x^2) / ( 1-8*x^2+x^4 ). - R. J. Mathar, Nov 11 2011

CROSSREFS

Cf. A057080, A001090, A041059, A004189, A000108

Sequence in context: A159078 A253090 A154226 * A030027 A082201 A038298

Adjacent sequences:  A177184 A177185 A177186 * A177188 A177189 A177190

KEYWORD

nonn,easy

AUTHOR

Mark Dols, May 04 2010

STATUS

approved

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Last modified August 9 13:57 EDT 2020. Contains 336323 sequences. (Running on oeis4.)