18576

Appears in sequences

• Number of monosubstituted alkanes C(n)H(2n+1)-X of the form shown in the Comments lines that are stereoisomers.at n=12A000622
• Numbers that are the sum of 7 positive 7th powers.at n=43A003374
• (1/2)*Sum{T(n,i): i=0,1,...,n}, where T is given by A048113.at n=16A048115
• McKay-Thompson series of class 25A for Monster.at n=30A058594
• Triangle T(n,k) = coefficient of x^n*y^k/(n!*k!) in 1/(1-x-y-x*y), read by rows in order 00, 10, 01, 20, 11, 02, ...at n=31A059446
• Triangle T(n,k) = coefficient of x^n*y^k/(n!*k!) in 1/(1-x-y-x*y), read by rows in order 00, 10, 01, 20, 11, 02, ...at n=32A059446
• Numbers k such that sigma (x) = k has exactly 11 solutions.at n=22A060678
• Array read by antidiagonals: T(n,m) = Sum m^max(k,n-k),k=0..n.at n=60A107661
• Expansion of s(q)^4 in powers of q where s() is a cubic AGM function.at n=14A133078
• Numbers of the form p^4*q^3*r where p, q, and r are distinct primes.at n=22A179698
• Number of (n+2) X (5+2) 0..3 arrays with every consecutive three elements in every row and column having exactly two distinct values, and in every diagonal and antidiagonal not having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=9A252692
• Numbers whose binary expansion equals the first n digits of the binary sequence A252488 whose run lengths are given by A001511 (the ruler function).at n=14A253585
• Union of all unique coefficients of all powers of the g.f. A(x) of this sequence, starting with A(0)=2 and A'(0)=3.at n=68A262975
• First differences of A275315.at n=17A275066
• First differences of A275316.at n=17A275472
• Numbers k such that uphi(k)*usigma(k) = uphi(k+1)*usigma(k+1), where uphi is the unitary totient function (A047994) and usigma the sum of unitary divisors (A034448).at n=13A297365
• L.g.f.: -log( Sum_{n=-oo..+oo} (-p)^n * (p*x)^(n^2) ) = Sum_{n>=1} a(n) * x^n/n, where p = sqrt(5).at n=5A337970
• a(n) = Sum_{1 <= x_1 <= x_2 <= x_3 <= x_4 <= x_5 <= x_6 <= n} gcd(x_1, x_2, x_3 , x_4, x_5, x_6, n).at n=12A343520
• Number of 2-matchings of the n-th centered square grid graph.at n=7A344679
• For 1<=x<=n, 1<=y<=n, write gcd(x,y) = u*x+v*y with u,v minimal; a(n) = n^4*s, where s is the population variance of the values of |u|.at n=10A345689