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

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A218208 Number of primes up to 10^n that are of the form (k-1)^2 + k^2. 4
1, 4, 10, 26, 68, 175, 461, 1225, 3349, 9266, 26516, 76334, 221763 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..13.

FORMULA

a(n) = sum(A218207(k), k=1..n)

MATHEMATICA

n = 0; cnt = 0; Table[While[n++; p = 2*n^2 - 2*n + 1; p < 10^e, If[PrimeQ[p], cnt++]]; n--; cnt, {e, 10}] (* T. D. Noe, Oct 23 2012 *)

CROSSREFS

Cf. A027861, A027862, A218207, A218210, A218212.

Sequence in context: A175658 A191605 A277236 * A207095 A126358 A200051

Adjacent sequences:  A218205 A218206 A218207 * A218209 A218210 A218211

KEYWORD

nonn,base

AUTHOR

Martin Renner, Oct 23 2012

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 December 7 19:34 EST 2021. Contains 349585 sequences. (Running on oeis4.)