31520

Appears in sequences

• a(0) = 1, a(1) = 2, a(n) = 4*a(n-1) - 2*a(n-2), n >= 2.at n=9A006012
• Expansion of g.f. (1 + x - 2*x^2 - x^3)/(1/2 - 2*x^2 + x^4).at n=17A030435
• Expansion of g.f. (1 + x - 2*x^2 - x^3)/(1 - 4*x^2 + 2*x^4).at n=18A030436
• a(0)=0; a(1)=1; a(n) = a(n-1) + (3 + (-1)^n)*a(n-2)/2.at n=19A062112
• Symmetric square table, read by antidiagonals, such that antidiagonal sums form the first row shifted left: T(0,0)=1, T(0,k) = Sum_{m=0..k-1} T(m,k-1-m) when k > 0; and T(n,k) = T(n-1,k) + T(n,k-1) when n > 0, k > 0.at n=55A084867
• a(n) = min{ m : sum_{n <= i <= m} 1/p_i > 1}, where p_i is the i-th prime = A000040(i).at n=26A092325
• a(n) = coefficient of x in (1+x)^n mod (1+x^4).at n=18A099587
• T(n,k) = Sum_{i=0..k} (-1)^(k-i)*binomial(k,i)*A000670(n-k+i).at n=32A122101
• Number of n X n symmetric matrices with nonnegative integer entries with each row sum i equal to i (1..n).at n=5A140722
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, 1), (0, 1, 1), (1, -1, 0), (1, 0, -1)}.at n=9A149030
• Number of binary strings of length n with equal numbers of 00010 and 00110 substrings.at n=16A164213
• Convolution of the central binomial coefficients A000984(n) and (-2)^n.at n=9A167481
• Number of (n+1) X 4 0..1 arrays with the number of clockwise edge increases in every 2 X 2 subblock differing from each horizontal or vertical neighbor.at n=15A205188
• T(n,k)=Number of nXk arrays of occupancy after each element stays put or moves to some king-move neighbor, with every occupancy equal to zero or two.at n=46A221337
• Records in A224796.at n=44A224719
• Number of (n+2)X(4+2) 0..3 arrays with every 3X3 subblock row and column sum not 2 4 5 or 7 and every diagonal and antidiagonal sum 2 4 5 or 7.at n=4A251872
• Number of (n+2)X(5+2) 0..3 arrays with every 3X3 subblock row and column sum not 2 4 5 or 7 and every diagonal and antidiagonal sum 2 4 5 or 7.at n=3A251873
• T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every 3X3 subblock row and column sum not 2 4 5 or 7 and every diagonal and antidiagonal sum 2 4 5 or 7.at n=31A251876
• T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every 3X3 subblock row and column sum not 2 4 5 or 7 and every diagonal and antidiagonal sum 2 4 5 or 7.at n=32A251876
• Number T(n,k) of permutations p of [n] with no fixed points where the maximal displacement of an element equals k; triangle T(n,k), n>=0, 0<=k<=n, read by rows.at n=53A259784