login

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 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A248578
a(n) = round(1/(Pi-n*sin(Pi/n))).
2
0, 1, 2, 3, 5, 7, 10, 12, 16, 19, 24, 28, 33, 38, 44, 50, 56, 63, 70, 77, 85, 94, 102, 112, 121, 131, 141, 152, 163, 174, 186, 198, 211, 224, 237, 251, 265, 280, 294, 310, 325, 341, 358, 375, 392, 410, 428, 446, 465, 484
OFFSET
1,3
COMMENTS
n*sin(Pi/n) is known as the Archimedean approximation to Pi, the present sequence measures [the reciprocal of] the error. See A248358 for the integer part.
MATHEMATICA
Table[Round[1/(Pi -n Sin[Pi/n])], {n, 50}] (* Harvey P. Dale, Jun 30 2022 *)
PROG
(PARI) a(n)=round(1/(Pi-n*sin(Pi/n)))
CROSSREFS
Sequence in context: A350102 A036607 A211520 * A062442 A036964 A067162
KEYWORD
nonn
AUTHOR
M. F. Hasler, Oct 08 2014
STATUS
approved