A139608 a(n) = 28*n + 8.

8, 36, 64, 92, 120, 148, 176, 204, 232, 260, 288, 316, 344, 372, 400, 428, 456, 484, 512, 540, 568, 596, 624, 652, 680, 708, 736, 764, 792, 820, 848, 876, 904, 932, 960, 988, 1016, 1044, 1072, 1100, 1128, 1156, 1184, 1212, 1240, 1268, 1296, 1324, 1352, 1380

Offset: 0

Author

Omar E. Pol, Apr 27 2008

Keywords

• easy
• nonn

Comments

Numbers of the 8th column of positive numbers in the square array of nonnegative and polygonal numbers A139600.

References

• A. H. Beiler, Recreations in the Theory of Numbers, Dover, NY, 1964, p. 189. - From N. J. A. Sloane, Dec 01 2012

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..10000
• Index to sequences related to polygonal numbers
• Index entries for linear recurrences with constant coefficients, signature (2,-1).

Crossrefs

Cf. A017005, A057145, A135628, A139600, A316466.

Programs

Magma

[4*(7*n + 2): n in [0..50]]; // Vincenzo Librandi, Jul 13 2011

Mathematica

Range[8, 7000, 28] (* Vladimir Joseph Stephan Orlovsky, Jul 13 2011 *)
LinearRecurrence[{2,-1},{8,36},50] (* or *) NestList[28+#&,8,50] (* Harvey P. Dale, Dec 14 2012 *)

PARI

a(n)=28*n+8 \\ Charles R Greathouse IV, Oct 05 2011

Formula

a(n) = A057145(n+2,8).

a(n) = 2*a(n-1) - a(n-2); a(0)=8, a(1)=36. - Harvey P. Dale, Dec 14 2012

G.f.: 4*(2+5*x)/(x-1)^2. - R. J. Mathar, Jul 28 2016

From Elmo R. Oliveira, Apr 16 2024: (Start)

E.g.f.: 4*exp(x)*(2 + 7*x).

a(n) = 4*A017005(n) = A135628(n) + 8 = A316466(n+1) - A316466(n). (End)