Sequences

Trajectory of 3 under map n->27n+1 if n odd, n->n/2 if n even.

Trajectory of 3 under map n->29n+1 if n odd, n->n/2 if n even.

Trajectory of 3 under map n->31n+1 if n odd, n->n/2 if n even.

Trajectory of 3 under map n->33n+1 if n odd, n->n/2 if n even.

Trajectory of 3 under map n->35n+1 if n odd, n->n/2 if n even.

Trajectory of 3 under map n->37n+1 if n odd, n->n/2 if n even.

Trajectory of 3 under map n->39n+1 if n odd, n->n/2 if n even.

Trajectory of 3 under map n->41n+1 if n odd, n->n/2 if n even.

Trajectory of 3 under map n->43n+1 if n odd, n->n/2 if n even.

Trajectory of 3 under map n->45n+1 if n odd, n->n/2 if n even.

Trajectory of 3 under map n -> 47n+1 if n odd, n->n/2 if n even.

Trajectory of 3 under map n->49n+1 if n odd, n->n/2 if n even.

a(n) = a(n-1) + sum of digits of n.

Numbers that contain only one nonzero digit.

Irregular triangle: row n is 1, 2, 3, 4, .., prime(n).

Triangle T(n,k) = prime(k) for k = 1..n.

a(n) = nextprime(3^n) - 2^n.

a(n) = nextprime(3^n) - nextprime(2^n).

(nextprime(3^n)-nextprime(2^n))/2.

Nextprime(4^n)-nextprime(2^n).

a(n) = (nextprime(4^n) - nextprime(2^n))/2.

nextprime(5^n)-nextprime(2^n).

(nextprime(5^n)-nextprime(2^n))/2.

Number of ways of writing n as a+b where a is abundant (or perfect), b is deficient (or perfect) and s(a)-a=b-s(b) (s(x)=sigma(x)-x).

Number of ways of writing n=a+b where |s(a)-a|=|s(b)-b|, s(x)=sigma(x)-x.

Numbers k such that A037134(k) = A037135(k).

Numbers k such that A037134(k) = A037135(k) > 0.

Numbers k such that sigma(totient(k)) + sigma(cototient(k)) = 2k.

Deficient numbers k such that k-s(k)-s(k-s(k)) = s(s(k))-s(k) or s(k-s(k))-k+s(k) = s(k)-s(s(k)).

Convolution of natural numbers n >= 1 with Fibonacci numbers F(k), for k >= 5.

Convolution of natural numbers n >= 1 with Fibonacci numbers F(k), for k >= -5, with F(-n)=(-1)^(n+1)*F(n);.

Erroneous version of A047995: Number of impartial misere games born on or before day n.

Numbers with at most 2 prime factors (counted with multiplicity).

Numbers with at most 3 prime factors (counted with multiplicity).

Expansion of 1/((1-x^2)(1-x^3)...(1-x^6)).

Numerators of Fourier coefficients of Eisenstein series of degree 2 and weight 10 when evaluated at Gram(A_2)*z.

Denominators of Fourier coefficients of Eisenstein series of degree 2 and weight 10 when evaluated at Gram(A_2)*z.

Numerators of Fourier coefficients of Eisenstein series of degree 2 and weight 12 when evaluated at Gram(A_2)*z.

Denominators of Fourier coefficients of Eisenstein series of degree 2 and weight 12 when evaluated at Gram(A_2)*z.

Fourier coefficients of Eisenstein series of degree 2 and weight 6 when evaluated at Gram(A_2)*z.

Smallest prime > n!.

Smallest prime > n!+1.

a(n) = p-n!, where p is the smallest prime > n!+1.

Largest prime < n!-1.

a(n) = n!-p, where p is the largest prime < (n!-1).

a(n) = 10^n*(10^n+1)/2.

Convolution of natural numbers n >= 1 with Fibonacci numbers F(k), for k >= 6.

Convolution of natural numbers n >= 1 with Fibonacci numbers F(k), for k >= -7, with F(-n)=(-1)^(n+1)*F(n).

Consider the trajectory of n under the iteration of a map which sends x to 3x - sigma(x) if this is >= 0; otherwise the iteration stops. The sequence gives values of n which eventually reach 0.

Squares in A037159.