login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A145607 Numbers k such that (3*(2*k + 1)^2 + 2)/5 is a square. 2
0, 4, 35, 279, 2200, 17324, 136395, 1073839, 8454320, 66560724, 524031475, 4125691079, 32481497160, 255726286204, 2013328792475, 15850904053599, 124793903636320, 982500325036964, 7735208696659395, 60899169248238199 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Square roots of (3*(2*k+1)^2+2)/5 are listed in A070997, therefore (3*(2*a(n) + 1)^2 + 2)/5 = A070997(n-1)^2.
LINKS
FORMULA
a(n+2) = 8*a(n+1) - a(n) + 3.
From R. J. Mathar, Oct 24 2008: (Start)
G.f.: x^2*(4 - x)/((1 - x)*(1 - 8*x + x^2)).
a(n) = (A057080(n-1)-1)/2. - R. J. Mathar, Oct 24 2008
CROSSREFS
Cf. A001091 (first differences).
Sequence in context: A261186 A104526 A174436 * A188527 A292190 A026304
KEYWORD
nonn,easy
AUTHOR
Richard Choulet, Oct 14 2008
EXTENSIONS
a(4) corrected, extended, definition corrected by R. J. Mathar, Oct 24 2008
Offset changed by Bruno Berselli, Apr 06 2018
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 12:26 EDT 2024. Contains 371254 sequences. (Running on oeis4.)