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A161365 3/2+5*n-5*(-1)^n/2. 0
9, 9, 19, 19, 29, 29, 39, 39, 49, 49, 59, 59, 69, 69, 79, 79, 89, 89, 99, 99, 109, 109, 119, 119, 129, 129, 139, 139, 149, 149, 159, 159, 169, 169, 179, 179, 189, 189, 199, 199, 209, 209, 219, 219, 229, 229, 239, 239, 249, 249, 259, 259, 269, 269, 279, 279, 289 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

LINKS

Index to sequences with linear recurrences with constant coefficients, signature (1,1,-1).

FORMULA

a(n)=10*n-a(n-1)-2, n>1.

a(n+1) = A017377(floor(n/2)).

G.f.: x*(9+x^2) / ( (1+x)*(x-1)^2 ).

CROSSREFS

Sequence in context: A168419 A112440 A022092 * A197497 A053456 A144424

Adjacent sequences:  A161362 A161363 A161364 * A161366 A161367 A161368

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 25 2009

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Last modified February 17 04:24 EST 2012. Contains 205978 sequences.