160020

Appears in sequences

• Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 40.at n=19A031718
• a(1) = a(2) = 1; a(n+2) = a(n+1) + a(n+1)^a(n).at n=5A058522
• Sum of distinct powers of 20; i.e., numbers with digits in {0,1} base 20; i.e., write n in base 2 and read as if written in base 20.at n=18A063012
• Given n colors, sequence gives number of ways to color the vertices of a square such that no edge has the same color on both of its vertices.at n=20A091940
• a(n) = 400*n^2 + 20.at n=20A158601
• Expansion of e.g.f.: 3*exp(3*x) / (4 - exp(3*x)).at n=6A201355
• Composite numbers n such that n+2 is also composite and such that (sopfr(n), sopfr(n+2)) is a twin prime pair. A001414 explains notation 'sopfr(n)'.at n=11A247048
• Let the binary expansion of n be [b_d, b_{d-1}, ..., b_3, b_2, b_1, b_0]_2, where (if n>0) b_d = 1, b_i = 0 or 1 for i<d. To get a(n) concatenate the decimal numbers 2^(b_i) (if b_i = 1) or 0 (if b_i = 0).at n=18A302205
• G.f. A(x) satisfies: A(x) = 1 + x*Sum_{n>=0} (A(x)^n - 1/A(x)^n)^n.at n=6A304637