|
Search: id:A144930
|
|
| |
|
| 1, 109, 11989, 1318681, 145042921, 15953402629, 1754729246269, 193004263686961, 21228714276319441, 2334965566131451549
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
Numbers n such that exists x in N : (x+1)^3-x^3=7*n^2 Richard Choulet (richardchoulet(AT)yahoo.fr), Oct 16 2008
|
|
FORMULA
|
a(n+2)=110*a(n+1)-a(n) [From Richard Choulet (richardchoulet(AT)yahoo.fr), Oct 16 2008]
a(n)=(1/2)*{[55+12*sqrt(21)]^n+[55-12*sqrt(21)]^n}+(3/28)*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*1 [From Richard Choulet (richardchoulet(AT)yahoo.fr), Oct 16 2008]
|
|
CROSSREFS
|
A144729, A144727, A144728 [From Richard Choulet (richardchoulet(AT)yahoo.fr), Oct 16 2008]
Sequence in context: A059936 A061724 A145852 this_sequence A125044 A096209 A163597
Adjacent sequences: A144927 A144928 A144929 this_sequence A144931 A144932 A144933
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Richard Choulet (richardchoulet(AT)yahoo.fr), Sep 25 2008
|
|
|
Search completed in 0.002 seconds
|
