19021

Appears in sequences

• a(n) = Sum_{k=1..n} k*phi(k).at n=44A011755
• Numbers k such that 3*k! - 1 is prime.at n=17A076134
• Square array, read by antidiagonal: T(n,k) = n*T(n,k-1)+(-1)^k*T(n,floor(k/2)).at n=59A089141
• Sieve performed by successive iterations of steps where step m is: keep m terms, remove the next 2 and repeat; as m = 1,2,3,.. the remaining terms form this sequence.at n=36A112560
• Sieve performed by successive iterations of steps where step m is: keep m terms, remove the next 4 and repeat; as m = 1,2,3,.. the remaining terms form this sequence.at n=12A112562
• a(n) is number of strings of length n that can be obtained by starting with abc and repeatedly doubling any substring in place and then discarding any string that contains two successive equal letters.at n=21A135017
• a(0)=2, a(n) = n^2+a(n-1).at n=38A153056
• a(n) = 36*n^2 - n.at n=22A157286
• a(n) = 529*n^2 - 23.at n=5A158633
• a(n) = A056520(n)+1 for n>0, a(0)=1.at n=38A179904
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 137", based on the 5-celled von Neumann neighborhood.at n=32A270276
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 822", based on the 5-celled von Neumann neighborhood.at n=32A272847
• G.f. A(x) satisfies: A(x) = 1 + x * A(x/(1 - 6*x)) / (1 - 6*x)^2.at n=5A351812
• G.f. satisfies A(x) = x + ( Sum_{n>=1} A(x^n) )^3.at n=11A382318