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!)
A132295 Sum of the nonsquare numbers not larger than n. 0
0, 2, 5, 5, 10, 16, 23, 31, 31, 41, 52, 64, 77, 91, 106, 106, 123, 141, 160, 180, 201, 223, 246, 270, 270, 296, 323, 351, 380, 410, 441, 473, 506, 540, 575, 575, 612, 650, 689, 729, 770, 812, 855, 899, 944, 990, 1037, 1085, 1085, 1135, 1186, 1238, 1291, 1345 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..54.

FORMULA

Let r = floor(sqrt(n)). Then a(n) = n(n+1)/2 - r(r+1)(2r+1)/6.

EXAMPLE

Let n=5.

The sum of the nonsquare numbers <= 5 is 2+3+5 = 10, the 5th entry in the sequence.

PROG

(PARI) sumNsq(n)= { for(x=1, n, r=floor(sqrt(x)); sq=r*(r+1)*(2*r+1)/6; sn=x*(x+1)/2; print1(sn-sq", ")) }

CROSSREFS

Cf. A000037, A086849.

Sequence in context: A081240 A184443 A238655 * A086651 A074495 A081467

Adjacent sequences:  A132292 A132293 A132294 * A132296 A132297 A132298

KEYWORD

nonn

AUTHOR

Cino Hilliard, Nov 07 2007

EXTENSIONS

Definition corrected. - R. J. Mathar, Sep 10 2016

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 September 29 04:42 EDT 2020. Contains 337420 sequences. (Running on oeis4.)