20274

Appears in sequences

• a(n) = Sum_{i,j,k in Z and i^2 + j^2 + k^2 <= n} i^2 + j^2 + k^2.at n=36A014203
• Fibonacci sequence beginning 2, 32.at n=15A022378
• Triangle read by rows: T(n,k) (0 <= k <= ceiling(n/2)-2) is the number of (1,1) steps starting at level k in all peakless Motzkin paths of length n (can be easily translated into RNA secondary structure terminology).at n=44A110238
• Numbers k such that binomial(3k, k) + 1 is prime.at n=26A125221
• a(n) = p(n)*p(n+2)-p(n+1), where p(n) is the n-th prime.at n=32A152530
• Numbers n which are concatenations n=x//y such that x^2+y^3 is a multiple of n.at n=36A162464
• Constant term of the reduction by x^2 -> x+1 of the polynomial p(n,x) defined at Comments.at n=19A192967
• a(n) = Sum_{i=0..n} digsum_5(i)^4, where digsum_5(i) = A053824(i).at n=35A231671
• Integers n such that 2n^2+1, 2n^3+1 and 2n^4+1 are prime.at n=23A239920
• Number of 2n-node unlabeled rooted trees with thinning limbs and root outdegree (branching factor) n.at n=14A244712
• Number of nX3 0..2 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.at n=3A280310
• Number of nX4 0..2 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.at n=2A280311
• T(n,k)=Number of nXk 0..2 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.at n=17A280313
• T(n,k)=Number of nXk 0..2 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.at n=18A280313
• G.f. satisfies: A(x) = Series_Reversion(x - x^3*A'(x)).at n=5A360976