|
Search: id:A067186
|
|
|
| A067186 |
|
Numbers n such that C(n) = (n^2 + n + 2)/2 is prime. |
|
+0
7
|
|
| 1, 3, 4, 7, 8, 11, 12, 16, 19, 20, 23, 27, 35, 40, 43, 44, 47, 51, 56, 60, 63, 64, 68, 71, 75, 76, 84, 88, 95, 96, 99, 100, 107, 111, 112, 131, 132, 135, 140, 148, 159, 163, 167, 168, 172, 175, 179, 184, 187, 200, 203, 207, 208, 211, 219, 223, 228, 236, 240, 251, 260
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
C(n) gives the maximum number of pieces in which a circular disc can be cut with n slices (A000124). C. Pickover calls the C(n)s "cake integers".
|
|
REFERENCES
|
Pickover, C. "Wonders of Numbers", Oxford Univ. Press, 2001; page 158, ch. 65.
|
|
LINKS
|
C. A. Pickover, "Wonders of Numbers, Adventures in Mathematics, Mind and Meaning," Zentralblatt review
|
|
FORMULA
|
a(n) = (A110872(n) - 1)/2. - Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 08 2005
|
|
EXAMPLE
|
C(7) = (7^2 + 7 + 2)/2 = 29, a prime, so 7 is a term of the sequence.
|
|
MATHEMATICA
|
Select[ Range[300], PrimeQ[(#^2 + # + 2)/ 2] &]
|
|
CROSSREFS
|
Cf. A000124, A055469, A110872, A110873.
Adjacent sequences: A067183 A067184 A067185 this_sequence A067187 A067188 A067189
Sequence in context: A003171 A028970 A058235 this_sequence A133675 A050122 A003657
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Feb 19 2002
|
|
EXTENSIONS
|
Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 19 2002
|
|
|
Search completed in 0.002 seconds
|
