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.
3, 41, 1159, 50049, 2908411, 212358985, 18665359119, 1917971421185, 225555471838387, 29871434052884841, 4398867465890529303, 712959801840558794625, 126115813138335816685995
Offset: 2
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.
Programs
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Mathematica
Array[Sum[2^j*Binomial[#1, j] Binomial[#2, j], {j, 0, Min[#1, #2]}] & @@ {#, #^2} &, 13] (* Michael De Vlieger, Jul 05 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
Comments