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A139609 a(n) = 36*n + 9. 3
9, 45, 81, 117, 153, 189, 225, 261, 297, 333, 369, 405, 441, 477, 513, 549, 585, 621, 657, 693, 729, 765, 801, 837, 873, 909, 945, 981, 1017, 1053, 1089, 1125, 1161, 1197, 1233, 1269, 1305, 1341, 1377, 1413, 1449, 1485, 1521, 1557, 1593, 1629, 1665, 1701 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Numbers of the 9th column of positive numbers in the square array of nonnegative and polygonal numbers A139600.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..5000

Index to sequences related to polygonal numbers

Index entries for linear recurrences with constant coefficients, signature (2,-1).

FORMULA

a(n) = A057145(n+2,9).

G.f.: 9*(1+3*x)/(x-1)^2. - R. J. Mathar, Jul 28 2016

MATHEMATICA

Range[9, 7000, 36] (* Vladimir Joseph Stephan Orlovsky, Jul 23 2011 *)

36*Range[0, 50]+9 (* or *) LinearRecurrence[{2, -1}, {9, 45}, 50] (* Harvey P. Dale, Jan 04 2018 *)

PROG

(MAGMA) [9*(4*n + 1): n in [0..60]]; // Vincenzo Librandi, Jul 23 2011

(PARI) a(n)=36*n+9 \\ Charles R Greathouse IV, Oct 05 2011

CROSSREFS

Sequence in context: A207359 A243090 A067536 * A321779 A068314 A152996

Adjacent sequences:  A139606 A139607 A139608 * A139610 A139611 A139612

KEYWORD

easy,nonn

AUTHOR

Omar E. Pol, Apr 27 2008

STATUS

approved

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Last modified July 28 10:29 EDT 2021. Contains 346326 sequences. (Running on oeis4.)