|
Search: id:A007575
|
|
|
| A007575 |
|
Number of stable towers of 2 X 2 LEGO blocks.
(Formerly M2675)
|
|
+0
2
|
|
| 1, 3, 7, 19, 53, 149, 419, 1191, 3403, 9755, 28077, 81097, 234861, 681697, 1982723, 5777375, 16861521, 49281525, 144222987, 422566835, 1239423303, 3638872529, 10693065215, 31448140529, 92558787745, 272612601065, 803448576111
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
REFERENCES
|
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
P. J. S. Watson, On "LEGO" towers, J. Rec. Math., 12 (No. 1, 1979-1980), 24-27.
Clifford A. Pickover, A Passion for Mathematics, Wiley, 2005; see p. 65.
|
|
MAPLE
|
seq(sum(coeff(product(1+x^k+x^(2*k), k=1..n), x, l), l=n*(n+1)/2-n..n*(n+1)/2+n), n=0..20); - Soren Eilers.
|
|
CROSSREFS
|
Cf. A007576.
Adjacent sequences: A007572 A007573 A007574 this_sequence A007576 A007577 A007578
Sequence in context: A090378 A007180 A059506 this_sequence A026299 A078481 A104522
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Simon Plouffe, N. J. A. Sloane (njas(AT)research.att.com), Robert G. Wilson v (rgwv(AT)rgwv.com)
|
|
|
Search completed in 0.002 seconds
|
