|
| |
|
|
A028375
|
|
Squares of (odd numbers not divisible by 5).
|
|
1
| |
|
|
1, 9, 49, 81, 121, 169, 289, 361, 441, 529, 729, 841, 961, 1089, 1369, 1521, 1681, 1849, 2209, 2401, 2601, 2809, 3249, 3481, 3721, 3969, 4489, 4761, 5041, 5329, 5929, 6241, 6561, 6889, 7569, 7921, 8281, 8649, 9409, 9801, 10201, 10609, 11449, 11881, 12321
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| Comment from Jonathan Vos Post, Mar 03 2010: Catalan stated empirically that the triple of any odd square not divisible by 5 is a sum of squares of three primes other than 2 and 3. [Reference?]
|
|
|
FORMULA
| a(n) = (A045572(n))^2.
a(n) = a(n-1) +2*a(n-4) -2*a(n-5) -a(n-8) +a(n-9). - R. J. Mathar, Sep 22 2009
G.f.: x*(1+8*x+40*x^2+32*x^3+38*x^4+32*x^5+40*x^6+8*x^7+x^8)/ ((1+x)^2 * (x^2+1)^2 * (1-x)^3). - R. J. Mathar, Sep 22 2009
|
|
|
CROSSREFS
| Sequence in context: A032589 A137175 * A167744 A032598 A110873 A167716
Adjacent sequences: A028372 A028373 A028374 * A028376 A028377 A028378
|
|
|
KEYWORD
| nonn,easy
|
|
|
AUTHOR
| ems (nibor(AT)ix.netcom.com)
|
|
|
EXTENSIONS
| Definition corrected - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 22 2009
|
| |
|
|
