19116

Appears in sequences

• Numbers k such that the squarefree part of k equals A062799(k).at n=28A069551
• The 28-cycle of the n => sigma(n)-n process, where sigma(n) is the sum of divisors of n (A000203).at n=1A072890
• a(n) = (7*2^n - 4(-1)^n)/3.at n=13A083595
• G.f.: (1+x^2)/((1-2x)(1-x-x^2)); a(n)=3a(n-1)-a(n-2)-2a(n-3); a(n)=5*2^n-L(n+3); a(n)=sum{k=0..n, (L(k)-0^k)2^(n-k)}.at n=12A099166
• Conjectured list of sociable numbers.at n=7A122726
• T(3n,2n), where T is the array in A127832.at n=4A127833
• 6 times heptagonal numbers: a(n) = 3*n*(5*n-3).at n=36A153786
• a(n) = a(n-1)+a(n-2)+a(n-3)+4*n^2-16*n+18 with a(0)=0, a(1)=0 and a(2)=1.at n=13A180669
• Coefficient of x in the reduction by x^2 -> x+1 of the polynomial p(n,x) defined at Comments.at n=17A192966
• Numbers k such that (2*10^k + 529)/9 is prime.at n=23A281734
• Largest integer that cannot be represented as x1^2 + ... + xk^2, where k >= 1, n <= x1 < ... < xk, and 1/x1 + ... + 1/xk = 1.at n=6A297896
• Triangle read by rows: T(n,k) = number of noncrossing path sets on n nodes up to rotation and reflection with k paths and isolated vertices allowed.at n=58A303868
• a(n) is the least term in A007602 such that the product of digits equals A342950(n) or 0 if no such number exists.at n=26A342952
• Conjectured list of numbers which are perfect, amicable, or sociable.at n=27A347770
• G.f. A(x) satisfies -1/x^55 = Sum_{n=-oo..+oo} A(x)^n * x^n * (1 - x^n)^(n+14).at n=5A384827