|
|
A028363
|
|
Total number of doubly-even self-dual binary codes of length 8n.
|
|
10
|
|
|
|
OFFSET
|
0,2
|
|
REFERENCES
|
F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier-North Holland, 1978, p. 631.
|
|
LINKS
|
|
|
FORMULA
|
a(n) = 2*Product_{i=1..4n-2} (2^i + 1).
|
|
MATHEMATICA
|
Join[{1}, Table[2*Product[2^i+1, {i, 4n-2}], {n, 6}]] (* Harvey P. Dale, May 08 2013 *)
Table[Product[2^i + 1, {i, 0, n/2 - 2}], {n, 8, 40, 8}] (* Nathan J. Russell, Mar 04 2016 *)
|
|
PROG
|
(Python)
for n in range(8, 50, 8):
product = 1
for i in range(n//2 - 1):
product *= 2**i + 1
print(product, end=", ")
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy,nice
|
|
AUTHOR
|
|
|
EXTENSIONS
|
There is an error in Eq. (75) of F. J. MacWilliams and N. J. A. Sloane, the lower subscript should be 1 not 0.
|
|
STATUS
|
approved
|
|
|
|