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A016897 a(n) = 5n + 4. 34
4, 9, 14, 19, 24, 29, 34, 39, 44, 49, 54, 59, 64, 69, 74, 79, 84, 89, 94, 99, 104, 109, 114, 119, 124, 129, 134, 139, 144, 149, 154, 159, 164, 169, 174, 179, 184, 189, 194, 199, 204, 209, 214, 219, 224, 229, 234, 239, 244, 249, 254, 259, 264, 269, 274, 279, 284 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Except for 1, 2, n such that sum_{k=1..n} (k mod 5)*C(n,k) is a power of 2. - Benoit Cloitre, Oct 17 2002

Numbers ending in 4 or 9. - Lekraj Beedassy, Jul 08 2006

a(n) is the set of numbers congruent to {4,9,14} mod 15. - Gary Detlefs, Mar 07 2010

Also the number of (not necessarily maximum) cliques in the n-book graph and (n+1)-ladder graph. - Eric W. Weisstein, Nov 29 2017

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..2000

Tanya Khovanova, Recursive Sequences

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 944

Eric Weisstein's World of Mathematics, Book Graph

Eric Weisstein's World of Mathematics, Clique

Eric Weisstein's World of Mathematics, Ladder Graph

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

FORMULA

G.f.: (4+x)/(1-x)^2. - Paul Barry, Feb 27 2003

a(n) = 2*a(n-1) - a(n-2), n>1. - Philippe Deléham, Nov 03 2008

a(n) = A131098(n+2) + n + 1. - Jaroslav Krizek, Aug 15 2009

a(n) = 10*n - a(n-1) + 3, n>0. - Vincenzo Librandi, Nov 20 2010

A000041(a(n)) == 0 mod 5 is the first of Ramanujan's congruences. - Ivan N. Ianakiev, Dec 29 2014

MAPLE

a[1]:=4:for n from 2 to 100 do a[n]:=a[n-1]+5 od: seq(a[n], n=1..57); # Zerinvary Lajos, Mar 16 2008

MATHEMATICA

Range[4, 500, 5] (* Vladimir Joseph Stephan Orlovsky, May 26 2011 *)

Table[5 n + 4, {n, 0, 20}] (* Eric W. Weisstein, Nov 29 2017 *)

5 Range[0, 20] + 4 (* Eric W. Weisstein, Nov 29 2017 *)

LinearRecurrence[{2, -1}, {9, 14}, {0, 20}] (* Eric W. Weisstein, Nov 29 2017 *)

CoefficientList[Series[(4 + x)/(-1 + x)^2, {x, 0, 20}], x] (* Eric W. Weisstein, Nov 29 2017 *)

PROG

(MAGMA) [5*n+4: n in [0..70]]; // Vincenzo Librandi, May 02 2011

(PARI) a(n)=5*n+4 \\ Charles R Greathouse IV, Sep 24 2015

CROSSREFS

Cf. A008587, A016861, A016873, A016885.

Sequence in context: A313116 A228176 A313117 * A189517 A190056 A313118

Adjacent sequences:  A016894 A016895 A016896 * A016898 A016899 A016900

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified November 16 00:11 EST 2018. Contains 317252 sequences. (Running on oeis4.)