20838

Appears in sequences

• Numbers k such that k^2 contains only digits {2,3,4}.at n=4A053916
• When squared gives number composed just of the digits 1, 2, 3, 4.at n=32A061677
• Numbers k such that k and k^2 use only the digits 0, 2, 3, 4 and 8.at n=27A136885
• Number of n X n arrays of squares of integers with every 2X2 subblock summing to 18.at n=9A159219
• Number of n X 3 0..2 arrays with every 1 immediately preceded by 0 to the left or above, no 0 immediately preceded by a 0, and every 2 immediately preceded by 0 1 to the left or above.at n=11A203176
• a(n) = n-th pi-based antiderivative of 7.at n=16A259168
• Array of coefficients A(n,k) of the formal power series P(n,x) read by upwards antidiagonals, where P(n,x) = Sum_{k>=0} A(n,k)*x^k = 1+x*P(n,x)^(1*n)+x^2*P(n,x)^(2*n) for n >= 0.at n=61A261440
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 222", based on the 5-celled von Neumann neighborhood.at n=36A270940
• Numbers k such that (82*10^k + 449)/9 is prime.at n=19A282809
• Relative of Hofstadter Q-sequence: a(n) = max(0, n+20830) for n <= 0; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 0.at n=10A283887
• Numbers k such that (298*10^k - 7)/3 is prime.at n=20A288484
• G.f. satisfies A(x) = 1 + x*A(x)^4*(1 + x*A(x)^4).at n=6A365183