Sequences

a(n) = (5*n)!/((2*n)!*(n!)^3).

Partial sums of A006206.

Golomb's sequence: a(n) is the number of times n occurs, starting with a(1) = 1.

Partial sums of A001462; also a(n) is the last occurrence of n in A001462.

Expansion of e.g.f. exp(-x - (1/2)*x^2).

Number of degree-n odd permutations of order 2.

Denominators of greedy Egyptian fraction expansion of Pi - 3.

Denominators of an expansion for Pi.

There are a(n) 2's between successive 1's.

Genocchi numbers (of first kind); unsigned coefficients give expansion of x*tan(x/2).

Number of degree-n permutations of order dividing 3.

Number of degree-n permutations of order exactly 3.

Number of degree-n permutations of order dividing 4.

Number of degree-n permutations of order exactly 4.

w such that w^3+x^3+y^3+z^3=0, w>|x|>|y|>|z|, is soluble.

a(n) = a(n-1) + n * a(n-2), where a(1) = 1, a(2) = 2.

Numbers that are not the sum of distinct positive cubes.

The nonnegative integers.

The negative integers.

Let p = A007645(n) be the n-th generalized cuban prime and write p = x^2 + 3*y^2; a(n) = x.

Let p = A007645(n) be the n-th generalized cuban prime and write p = x^2 + 3*y^2; a(n) = y.

Numbers that are the sum of 2 squares.

Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^4 in powers of x.

Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^5 in powers of x.

Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^6 in powers of x.

Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^7 in powers of x.

Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^8 in powers of x.

Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^9 in powers of x.

Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^10 in powers of x.

a(n) = -n.

Expansion of {Product_{j>=1} (1 - (-x)^j) - 1}^12 in powers of x.

Opus numbers of Beethoven's nine symphonies.

Clock chimes with a quarter-hour bell.

Erroneous version of A000637.

Numbers k such that phi(k) = phi(k+2).

Number of symmetric 0-1 (n+1) X (n+1) matrices with row sums 2 and first row starting 1,1 for n > 0, a(0)=1.

Number of 4 X 4 matrices with nonnegative integer entries and row and column sums equal to n.

Triangle of coefficients of Bessel polynomials (exponents in decreasing order).

Triangle a(n,k) (n >= 0, 0 <= k <= n) of coefficients of Bessel polynomials y_n(x) (exponents in increasing order).

Number of n X n matrices with exactly 2 1's in each row and column, other entries 0.

Number of stochastic matrices of integers: n X n arrays of nonnegative integers with all row and column sums equal to 3.

Number of n X n 0-1 matrices with all column and row sums equal to 3.

Largest number requiring n syllables in English (U.S.) - not well-defined, but the next term may be twelve millillion, too large to write down here.

Largest number requiring n syllables in English (U.K.) - not well-defined, but the next term may be twelve millillion, too large to write down here.

a(n) = (3*n+1)*(3*n+2).

a(n) = (4*n+1)*(4*n+2)*(4*n+3).

a(n) is the number of c-nets with n+1 vertices and 2n edges, n >= 1.

a(n) is the number of c-nets with n+1 vertices and 2n+1 edges, n >= 1.

a(n) is the number of c-nets with n+1 vertices and 2n+2 edges, n >= 1.

a(n) = (5*n + 1)*(5*n + 2)*(5*n + 3).