20788

Appears in sequences

• Number of 2 X 2 nonsingular 0..n matrices with rows and columns in increasing order.at n=14A183762
• Number of n element 1..n arrays with each element the minimum of 6 adjacent elements of a permutation of 1..n+5 of n+5 elements.at n=7A217889
• Number of binary "privileged words" of length n.at n=20A231208
• Numbers missing from A001033 despite satisfying the necessary congruence conditions (see comments).at n=33A274470
• Expansion of (1/x) * Series_Reversion( x * (1-3*x)^3 / (1-2*x) ).at n=4A371363
• Irregular table read by rows: T(n,k) is the number of k-gons, k>=3, among all distinct circles that can be constructed from the 4 vertices and the equally spaced 4*n points placed on the sides of a square, using only a compass.at n=21A372980
• E.g.f. satisfies A(x) = 1/(2 - exp(x*A(x)^2))^2.at n=4A377425
• a(n) = 25*n^2/2 - 11*n/2 + 1.at n=41A383465
• Numbers k such that A003415(k) == A276085(k) (mod 2310), where A003415 is the arithmetic derivative and A276085 is the primorial base log-function.at n=21A391864