|
Search: id:A123720
|
|
|
| A123720 |
|
a(n) = 2^n + 2^(n-1) - n. |
|
+0
2
|
|
| 2, 4, 9, 20, 43, 90, 185, 376, 759, 1526, 3061, 6132, 12275, 24562, 49137, 98288, 196591, 393198, 786413, 1572844, 3145707, 6291434, 12582889, 25165800, 50331623, 100663270, 201326565, 402653156, 805306339, 1610612706, 3221225441
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
a(n) = A007283(n-1) - n.
|
|
FORMULA
|
O.g.f.: x(2-4x+3x^2)/((1-x)^2*(1-2x)). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 08 2008
|
|
MATHEMATICA
|
lst={}; Do[AppendTo[lst, 2^n+2^(n-1)-n], {n, 5!}]; lst ...and/or... s=2; lst={s}; Do[s+=s+n++; AppendTo[lst, s], {n, 0, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Oct 25 2008]
|
|
PROGRAM
|
(PARI) for(n=1, 31, print1(2^n+2^(n-1)-n, ", "))
|
|
CROSSREFS
|
Cf. A007283.
Sequence in context: A101338 A018102 A018103 this_sequence A034007 A109975 A129891
Adjacent sequences: A123717 A123718 A123719 this_sequence A123721 A123722 A123723
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Oct 09 2006
|
|
|
Search completed in 0.002 seconds
|
