A017245 a(n) = 9*n + 7.

7, 16, 25, 34, 43, 52, 61, 70, 79, 88, 97, 106, 115, 124, 133, 142, 151, 160, 169, 178, 187, 196, 205, 214, 223, 232, 241, 250, 259, 268, 277, 286, 295, 304, 313, 322, 331, 340, 349, 358, 367, 376, 385, 394, 403, 412, 421, 430, 439, 448, 457, 466, 475, 484

Offset

0,1

Comments

Numbers whose digital root is 7. - Halfdan Skjerning, Mar 15 2018

Links

Table of n, a(n) for n=0..53.

Tanya Khovanova, Recursive Sequences

J. Laroche & N. J. A. Sloane, Correspondence, 1977

Leo Tavares, Illustration: Triple Triangular Frames

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

Formula

a(n)^2 = A156676(n+1) + A017137(n). - Reinhard Zumkeller, Jul 13 2010

a(n) = 18*n - a(n-1) + 5, with a(0)=7. - Vincenzo Librandi, Dec 24 2010

G.f.: (7+2*x)/(1-x)^2. - Vincenzo Librandi, Apr 30 2015

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>2. - Vincenzo Librandi, Apr 30 2015

Mathematica

Range[7, 1000, 9] (* Vladimir Joseph Stephan Orlovsky, May 28 2011 *)
Table[9 n + 7, {n, 0, 70}] (* or *) CoefficientList[Series[(7 + 2 x)/(1 - x)^2, {x, 0, 60}], x] (* Vincenzo Librandi, Apr 30 2015 *)

Prog

(Magma) [9*n+7: n in [0..60]]; // Vincenzo Librandi, Apr 30 2015
(PARI) vector(100, n, 9*n-2) \\ Derek Orr, Apr 30 2015

Crossrefs

Cf. A008591, A017233.

Sequence in context: A273159 A043481 A217009 * A052221 A119461 A326664

Adjacent sequences: A017242 A017243 A017244 * A017246 A017247 A017248

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved