login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A086601 Triangular numbers + 1 squared. 7
1, 4, 16, 49, 121, 256, 484, 841, 1369, 2116, 3136, 4489, 6241, 8464, 11236, 14641, 18769, 23716, 29584, 36481, 44521, 53824, 64516, 76729, 90601, 106276, 123904, 143641, 165649, 190096, 217156, 247009, 279841, 315844, 355216, 398161 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..35.

Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).

FORMULA

a(n) = (A000217(n)+1)^2.

a(n) = (binomial(2+n,2)-binomial(n,1))^2. - Zerinvary Lajos, May 30 2006, corrected by R. J. Mathar, May 14 2014

a(n) = A000124(n)^2. - Omar E. Pol, Oct 30 2007

a(n) = 1+A061316(n). Zerinvary Lajos, Apr 25 2008

G.f.: ( -1+x-6*x^2+x^3-x^4 ) / (x-1)^5 . - R. J. Mathar, May 14 2014

EXAMPLE

a(5)=(t(5)+1)^2=16^2=256

MAPLE

A086601 := proc(n)

    (n+2+n^2)^2 /4 ;

end proc:

seq(A086601(n), n=0..20) ; # R. J. Mathar, May 14 2014

PROG

(PARI) w=vector(40, i, (t(i)+1)^2)

CROSSREFS

Cf. A000124.

Sequence in context: A222936 A119005 A237986 * A224147 A227266 A114185

Adjacent sequences:  A086598 A086599 A086600 * A086602 A086603 A086604

KEYWORD

nonn,easy

AUTHOR

Jon Perry, Jul 23 2003

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified June 28 16:56 EDT 2017. Contains 288839 sequences.