A046948 Sizes of successive balls in E_8 lattice.

1, 241, 2401, 9121, 26641, 56881, 117361, 199921, 340321, 522001, 794161, 1113841, 1604401, 2131921, 2874961, 3721681, 4845121, 6024481, 7659601, 9306001, 11513521, 13825201, 16702321, 19622641, 23553841, 27334081

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Crossrefs

Partial sums of A004009.

Programs

PARI

B=1; th=[ 1 ]; bl=[ 1 ]; for (n=1,10000,t1=divisors(n); t2=0; for (i=1,length(t1),t2=t2+t1[ i ]^3); t3=240*t2; th=concat(th,t3); B=B+t3; bl=concat(bl,B)); th; bl;

Formula

a(n) ~ 2 * Pi^4 * n^4 / 3. - Vaclav Kotesovec, Jan 14 2024