Sequences

Theta series of 12-dimensional Coxeter-Todd lattice K_12.

Theta series of D_4 lattice; Fourier coefficients of Eisenstein series E_{gamma,2}.

Theta series of hexagonal close-packing.

Theta series of body-centered cubic (b.c.c.) lattice.

Norms of vectors in the b.c.c. lattice.

Theta series of face-centered cubic (f.c.c.) lattice.

Theta series of planar hexagonal lattice A_2.

Theta series of E_8 lattice with respect to deep hole.

Theta series of square lattice (or number of ways of writing n as a sum of 2 squares). Often denoted by r(n) or r_2(n).

a(0) = 0; for n > 0, a(n) = (a(n-1) + 1)^2.

Theta series of square lattice with respect to edge.

Theta series of packing P_{10c}.

Primes of the form (10^k - 1)/9. Also called repunit primes or repdigit primes.

Indices of prime repunits: numbers k such that 11...111 (with k 1's) = (10^k - 1)/9 is prime.

Theta series of b.c.c. lattice with respect to deep hole.

Theta series of b.c.c. lattice with respect to long edge.

Number of perfect quadratic forms or lattices in dimension n.

Number of arithmetic n-dimensional crystal classes.

Number of geometric n-dimensional crystal classes.

Number of n-dimensional space groups.

Erroneous version of A256413.

Number of n-dimensional crystal systems.

Number of n-dimensional crystal families.

Theta series of lattice A_2 tensor E_8 (dimension 16, det. 6561, min. norm 4). Also theta series of Eisenstein version of E_8 lattice.

Theta series of Leech lattice with respect to deep hole of type A_1.

The coding-theoretic function A(n,4,5).

The coding-theoretic function A(n,4,6).

The coding-theoretic function A(n,6,4).

The coding-theoretic function A(n,6,5).

The coding-theoretic function A(n,6,6).

Inversion of A000257.

Scaled sums of odd reciprocals: a(n) = (2*n + 1)!!*(Sum_{k=0..n} 1/(2*k + 1)).

Periods of reciprocals of A006883, starting with first nonzero digit.

The coding-theoretic function A(n,8,8).

The classic football pool problem: size of minimal covering code in {0,1,2}^n with covering radius 1.

Minimal size of binary code of length n such that every vector is within distance 1 of at least 2 codewords.

Theta series of extremal 3-modular even 24-dimensional lattice with minimal norm 6 and det = 3^12.

The coding-theoretic function A(n,10,9).

Theta series of 14-dimensional extremal 3-modular lattice with det 3^7, minimal norm 4, group 2 X G_2(3).

Erroneous version of A006967.

Numbers of the form 2^j + 3^k, for j and k >= 0.

Primes of the form 2^a + 3^b.

The coding-theoretic function A(n,14,8).

For m=2,3,..., write m in bases 2,3,..,m.

Expansion of (1-x)/((1+x)*(1-2*x)*(1-3*x)).

((p-1)/2)! mod p for odd primes p.

The coding-theoretic function A(n,14,12).

Expansion of (1-x)/( (1+x)*(1-2*x)*(1-3*x)*(1-4*x)).

Expansion of (1-x)/( (1+x)*(1-2*x)*(1-3*x)*(1-4*x)*(1-5*x)).

a(n) gives position of first n in A057561.