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A181675 V(n,n^2), where V is the number of integer points in an n-dimensional sphere of Lee-radius n^2 centered at the origin. 2
3, 41, 1159, 50049, 2908411, 212358985, 18665359119, 1917971421185, 225555471838387, 29871434052884841, 4398867465890529303, 712959801840558794625, 126115813138335816685995 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,1
COMMENTS
Since V(n,d) is symmetric, we have V(n,n^2) = V(n^2,n).
LINKS
Solomon W. Golomb and Lloyd R. Welch, Perfect Codes in the Lee Metric and the Packing of Polyominoes, SIAM Journal on Applied Mathematics Vol. 18, No. 2 (Mar. 1970), pp. 302-317.
Milan Janjić, On Restricted Ternary Words and Insets, arXiv:1905.04465 [math.CO], 2019.
FORMULA
V(n,d) = Sum_{j=0..min(n,d)} 2^j * binomial(n,j)*binomial(d,j).
a(n) ~ exp(n-2) * (2*n)^(n - 3/2) / sqrt(Pi). - Vaclav Kotesovec, Feb 13 2021
MATHEMATICA
Array[Sum[2^j*Binomial[#1, j] Binomial[#2, j], {j, 0, Min[#1, #2]}] & @@ {#, #^2} &, 13] (* Michael De Vlieger, Jul 05 2019 *)
CROSSREFS
V(n, n) = A001850, V(n, 2n) = A026000 and V(n, 3n) = A026001.
Sequence in context: A007313 A222524 A241704 * A012053 A012162 A012225
KEYWORD
easy,nonn
AUTHOR
Antonio Campello, Nov 04 2010
STATUS
approved

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Last modified July 21 00:40 EDT 2024. Contains 374462 sequences. (Running on oeis4.)