20821

Appears in sequences

• Numbers whose base-2 representation has exactly 13 runs.at n=26A043580
• a(n) = round(sqrt(Fibonacci(n))).at n=43A100665
• Unlabeled version of A055203: number of different relations between n intervals (of nonzero length) on a line, up to permutation of intervals.at n=5A121316
• Alternating row sums of triangle A134280 (S2(6)').at n=4A134282
• Numbers such that the digital sum base 2 and the digital sum base 3 and the digital sum base 4 all are equal.at n=7A135122
• Number of ordered triples (w,x,y) with all terms in {1,...,n} and w^4<x^4+y^4.at n=31A211652
• Smallest j such that j*2*p(n)^3-1=q is prime, j*2*p(n)*q^2-1=r, j*2*p(n)*r^2-1=s, where r and s are also prime.at n=37A224611
• Smallest positive multiple of n whose base-4 representation contains only 0's and 1's.at n=46A244955
• Triangle read by rows: number of generic n-rook placements with k rooks below the main diagonal.at n=14A269744
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 931", based on the 5-celled von Neumann neighborhood.at n=24A273790
• Decimal representation of the x-axis, from the left edge to the origin, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 99", based on the 5-celled von Neumann neighborhood.at n=34A278872
• Decimal representation of the x-axis, from the origin to the right edge, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 203", based on the 5-celled von Neumann neighborhood.at n=14A279811
• Array read by antidiagonals: A(n,k) is the number of binary matrices with k columns and any number of nonzero rows with n ones in every column and columns in nonincreasing lexicographic order.at n=30A330942
• a(n) is the least term of A126684 of the form k*n with k > 0.at n=47A377413
• Antidiagonal sums of A343052.at n=49A379703