|
Search: id:A144929
|
|
|
| A144929 |
|
Numbers n such that there exists an integer k with (n+1)^3-n^3=7*k^2. |
|
+0
4
|
|
| 1, 166, 18313, 2014318, 221556721, 24369225046, 2680393198393, 294818882598238, 32427396692607841, 3566718817304264326
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
FORMULA
|
a(n+2)=110*a(n+1)-a(n)+54
a(n)=-(1/2)+(3/4)*{[55+12*sqrt(21)]^n+[55-12*sqrt(21)]^n}+(1/6)*sqrt(21)*{[55+12*sqrt(21)]^n-[55-12*sqrt(21)]^n }, with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Nov 25 2008]
|
|
EXAMPLE
|
a(1)=1 because 2^3-1^3=7=7*1^2
|
|
CROSSREFS
|
Cf. A144927, A144928, A144930.
A144930, A144927, A144928 [From Richard Choulet (richardchoulet(AT)yahoo.fr), Oct 16 2008]
Sequence in context: A033675 A144380 A011815 this_sequence A163398 A097400 A142664
Adjacent sequences: A144926 A144927 A144928 this_sequence A144930 A144931 A144932
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Richard Choulet (richardchoulet(AT)yahoo.fr), Sep 25 2008
|
|
EXTENSIONS
|
Numbers x such that there exists an integer n with (x+1)^3-x^3=7*n^2. Richard Choulet (richardchoulet(AT)yahoo.fr), Oct 16 2008
|
|
|
Search completed in 0.002 seconds
|
