21596

Appears in sequences

• Numbers k such that 111*2^k+1 is prime.at n=14A032405
• 6*a(n) is the gap between sexy prime triples in the n-th sexy prime triple triple whose initial term is 5.at n=8A090775
• Number of (undirected) cycles in the graph with nodes labeled 1..n, and nodes i and j joined by an edge if i divides j or vice versa.at n=19A161787
• a(1)=1, a(2)=2; thereafter a(n) = a(n-1) + a(n-1-(number of even terms so far)) + a(n-1-(number of odd terms so far)).at n=44A249039
• Number of length 3 1..(n+2) arrays with no leading partial sum equal to a prime.at n=35A254541
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 782", based on the 5-celled von Neumann neighborhood.at n=43A273536
• a(n) is the number of nonnegative integers that can be represented in a 7-segment display by using only n segments (version A006942).at n=21A331529
• Expansion of Sum_{k>0} x^(2*k)/(1 - (k*x)^k)^3.at n=13A363651
• a(n) = Sum_{k=1..n-1} sigma_2(k) * sigma_3(n-k).at n=9A376290