login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A154576 a(n) = 2*n^2 + 14*n + 5. 2
21, 41, 65, 93, 125, 161, 201, 245, 293, 345, 401, 461, 525, 593, 665, 741, 821, 905, 993, 1085, 1181, 1281, 1385, 1493, 1605, 1721, 1841, 1965, 2093, 2225, 2361, 2501, 2645, 2793, 2945, 3101, 3261, 3425, 3593, 3765, 3941, 4121, 4305, 4493, 4685, 4881 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Seventh diagonal in A144562. 2*a(n) + 39 is a square.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

FORMULA

G.f.: x*(3-x)*(7-5*x)/(1-x)^3. - Bruno Berselli, Dec 07 2011

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - Vincenzo Librandi, Feb 22 2012

MATHEMATICA

LinearRecurrence[{3, -3, 1}, {21, 41, 65}, 50] (* Vincenzo Librandi, Feb 22 2012 *)

PROG

(MAGMA) I:=[21, 41, 65]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..40]]; // Vincenzo Librandi, Feb 22 2012

(PARI) for(n=1, 40, print1(2*n^2 + 14*n + 5", ")); \\ Vincenzo Librandi, Feb 22 2012

CROSSREFS

Cf. A144562, A154577.

Sequence in context: A104393 A261522 A215145 * A173960 A147273 A195034

Adjacent sequences:  A154573 A154574 A154575 * A154577 A154578 A154579

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Jan 12 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 24 01:16 EST 2020. Contains 332195 sequences. (Running on oeis4.)