Sequences

Number of n-node rooted labeled trees with deg <= 4 at root and outdegree <= 2 elsewhere.

Shapes of height-balanced AVL trees of height at most 5 with n nodes.

Decimal expansion of 1/98019801.

Decimal expansion of 1/980198019801.

Decimal expansion of 1/9801980198019801.

Numbers k such that 5*k + 1 is a square.

Numbers of the form 2^i*3^j, i+j even.

Hati numbers: of form 2^i*3^j*k, i+j even, (k,6)=1.

Duplicate of A000633.

G.f.: A(x) = x*cycle_index(S5, B(x)-1), where B(x) is g.f. for A000598.

Number of isomers C_n H_{2n} without double bonds.

Number of stereoisomers of acyclic hydrocarbons with n carbon atoms.

Number of stereoisomers of all n-node acyclic hydrocarbons with no triple bonds.

G.f.: A(x) = (1/2)*x*(B(x)^2+B(x^2)), where B(x) = g.f. for A000600.

G.f. satisfies A(x) = 1 + x*A(x)^2*A(x^2).

Used by Polya in calculating A000598.

Used by Polya in calculating A000598.

Used by Polya in calculating A000598.

a(n) = n^n - n!.

Expansion of C in Egyptian fractions, where C is the prime constant A051006.

T(n+2,2) with T as in A036355.

T(n+3,3) with T as in A036355.

T(n+4,4) with T as in A036355.

T(n+5,5) with T as in A036355.

List of single-heap P-positions in Grundy's game.

Single-heap P-positions in misere version of Grundy's game.

a(n) = Product_{i=0..n} (3*i+1)! / (n+i)!.

Number of distinct n-digit suffixes of base-10 squares not containing the digit 0.

Product of a prime and the previous number.

Product of a prime and the following number.

Compositorial numbers: product of first n composite numbers.

T(2n,n) with T as in A036355.

Number of Gaussian integers z = a + bi satisfying n-1 < |z| <= n.

a(n) = (1/4)*A036693(n) for n >= 1.

a(n)=number of Gaussian integers z=a+bi satisfying |z|<=n, b>=0.

a(n)=number of Gaussian integers z=a+bi satisfying n-1<|z|<=n, b>=0.

a(n)=number of Gaussian integers z=a+bi satisfying n-1<|z|<=n, a>=0, b>=0.

a(n) is the number of Gaussian integers z=a+bi satisfying |z|<=n, a>0, b>=0.

Duplicate of A036694.

Number of Gaussian integers z=a+bi satisfying |z|<=n, a>=0, 0<=b<a.

a(n)=number of Gaussian integers z=a+bi satisfying n-1<|z|<=n, a>=0, 0<=b<a.

a(n)=number of Gaussian integers z=a+bi satisfying |z|<=n, a>=0, 0<=b<=a.

a(n)=number of Gaussian integers z=a+bi satisfying n-1<|z|<=n, a>=0, 0<=b<=a.

a(n)=number of Gaussian integers z=a+bi satisfying |z|<=n+1/2.

Number of Gaussian integers z=a+bi satisfying n - 1/2 < |z| <= n + 1/2.

a(n)=number of Gaussian integers z=a+bi satisfying n - 1/2 < |z| <= n + 1/2, a>0, b>=0.

a(n)=number of Gaussian integers z=a+bi satisfying |z|<=n+1/2, b>=0.

a(n)=number of Gaussian integers z=a+bi satisfying n-1/2<|z|<=n+1/2, b>=0.

a(n)=number of Gaussian integers z=a+bi satisfying |z|<=n+1/2, a>=0, b>=0.

a(n)=number of Gaussian integers z=a+bi satisfying n-1/2<|z|<=n+1/2, a>=0, b>=0.