A164284 a(n) = 15*n-7.

8, 23, 38, 53, 68, 83, 98, 113, 128, 143, 158, 173, 188, 203, 218, 233, 248, 263, 278, 293, 308, 323, 338, 353, 368, 383, 398, 413, 428, 443, 458, 473, 488, 503, 518, 533, 548, 563, 578, 593, 608, 623, 638, 653, 668, 683, 698, 713, 728, 743, 758, 773, 788

Offset: 1

Author

Vincenzo Librandi, Aug 12 2009

Keywords

• nonn
• easy

Comments

Alternative definition: numbers m such that (13*m+1)/15 is an integer.

The previous comment is the case t=0 of ((13-t*(t+1))*m + t*(t+1)/2 + 1)/15, where t = 0, 1, 2 or 3. - Bruno Berselli, Feb 22 2016

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (2,-1).

Crossrefs

Cf. A008597, A139606.

Cf. similar sequences with closed form (2*k-1)*n+k listed in A269044.

Programs

Mathematica

Range[8, 1000, 15] (* Vladimir Joseph Stephan Orlovsky, May 31 2011 *)
LinearRecurrence[{2,-1},{8,23},60] (* Harvey P. Dale, Dec 25 2016 *)

PARI

x='x+O('x^50); Vec(x*(8+7*x)/(x-1)^2) \\ G. C. Greubel, Sep 12 2017

Python

def a(n): return 15*n - 7
print([a(n) for n in range(1, 54)]) # Michael S. Branicky, Aug 23 2021

Formula

G.f.: x*(8+7*x)/(x-1)^2.

E.g.f.: 7 + (15*x - 7)*exp(x). - G. C. Greubel, Sep 12 2017

Extensions

Definition simplified by R. J. Mathar, Aug 21 2009