|
Search: id:A117718
|
|
|
| A117718 |
|
Number of heptagonal numbers with n digits. |
|
+0
1
|
|
| 3, 4, 14, 43, 137, 432, 1368, 4324, 13676, 43245, 136755, 432455, 1367545, 4324555, 13675445, 43245553, 136754447, 432455532, 1367544468, 4324555320, 13675444680, 43245553203, 136754446797, 432455532033, 1367544467967
(list; graph; listen)
|
|
|
OFFSET
|
0,1
|
|
|
EXAMPLE
|
a(4)=43 because there are 43 heptagonal numbers with 4 digits.
|
|
MAPLE
|
Digits := 20: A117718 := proc(n) if n = 1 then 3; else ceil(3/10*(1+sqrt(1+40*10^n/9))-1) - ceil(3/10*(1+sqrt(40*10^(n-1)/9))) +1 ; fi ; end: seq(A117718(n), n=1..30) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 22 2008
|
|
CROSSREFS
|
Cf. A000566.
Sequence in context: A057433 A006074 A081714 this_sequence A086826 A130409 A157351
Adjacent sequences: A117715 A117716 A117717 this_sequence A117719 A117720 A117721
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
Luc Stevens (lms022(AT)yahoo.com), Apr 13 2006
|
|
EXTENSIONS
|
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 22 2008
|
|
|
Search completed in 0.002 seconds
|
