22720

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 75.at n=38A031573
• Number of different products (including the empty product) of any subset of {1, 2, 3, ..., n}.at n=19A060957
• Numbers n such that p(6n) is prime, where p(n) is the number of partitions of n.at n=41A111036
• Numbers k such that 1*k + 1, 3*k + 1, 9*k + 1, 27*k + 1 are all primes.at n=22A112041
• Riordan array [sec(x), log(sec(x) + tan(x))].at n=48A147309
• Riordan array [1,log(sec(x)+tan(x))].at n=59A147312
• Quartic product sequence: a(n) = 2^n*Product_{k=1..(n-1)/2} (1 + m*cos(k*Pi/n)^2 + q*cos(k*Pi/n)^4), with m=6, q=4.at n=8A152104
• Triangle read by rows: T(n,k) is the number of cycle-up-down permutations of {1,2,...,n} having k excedances (0<=k<=floor(n/2)).at n=28A186368
• Number of (n+2) X (5+2) 0..1 arrays with every 2 X 2 and 3 X 3 subblock diagonal maximum minus antidiagonal minimum nondecreasing horizontally and vertically.at n=7A253507
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 397", based on the 5-celled von Neumann neighborhood.at n=31A271691
• Number of compositions of n if only the order of the odd numbers matter.at n=21A275548
• Number of solutions to x^2 + y^2 + z^2 + w^2 <= n^2, where x, y, z, w are positive odd integers.at n=33A349611
• Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,0) = 0^n and T(n,k) = k * Sum_{r=0..n} binomial(n,r) * binomial(3*n+3*r+k,n)/(3*n+3*r+k) for k > 0.at n=40A378240