21982

Appears in sequences

• Least k such that the first k terms of the Kolakoski sequence (A000002) contain n more 2's than 1's.at n=13A025503
• Numbers k such that sigma(phi(k)) = sigma(k) where sigma is the sum of divisors function A000203 and phi is the Euler totient function A000010.at n=7A033631
• Numbers n such that sigma(sigma(phi(n))) = sigma(sigma(n)).at n=27A172466
• a(n) = n*(n^2 - 3*n + 4).at n=29A242659
• a(0)=1; for n >= 1, a(n) is the number of subsets of [a(0), a(1), ..., a(n-1)] whose sum is equal to a(n-1).at n=30A265853
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 462", based on the 5-celled von Neumann neighborhood.at n=40A272311
• Position of first appearance of each integer in A088568 (number of 1's minus number of 2's in first n terms of A000002).at n=25A288605
• a(n) = index where A088568 (or equally A294448) first reaches or exceeds n in magnitude.at n=13A294449
• Place two n-gons with radii 1 and 2 concentrically, forming an annular area between them. Connect all the vertices with line segments that lie entirely within that area. Then a(n) is the number of regions in that figure.at n=26A337700
• Number of distinct ways of expressing n using only addition, multiplication (with all factors greater than 1), necessary parentheses, and the number 1.at n=42A373446