23018

Appears in sequences

• a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (composite numbers), t = (odd natural numbers).at n=41A024590
• a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (composite numbers), t = (odd natural numbers).at n=40A025104
• Number of double nodes (exactly two nodes on that level) for all Motzkin paths of length n.at n=13A051485
• Boris Stechkin's function.at n=37A055004
• a(n) = Sum_{y=1..n} Sum_{x=1..n} floor((x^k + y^k)^(1/k)) with k = 2.at n=30A211791
• G.f. A(x) satisfies: A(x + A(x)*A(-x)) = x - A(x)*A(-x).at n=7A295767
• Number of compositions of n with equal circular differences up to sign.at n=50A325558
• Number of excursions of length n with Motzkin-steps avoiding the consecutive steps UH, HD and DU.at n=19A329698
• For 1<=x<=n, 1<=y<=n, write gcd(x,y) = u*x+v*y with u,v minimal; a(n) = sum of the values of u^2+v^2.at n=27A345434
• Number of integer partitions of n such that, for all parts x, x - 1 or x + 1 is also a part.at n=52A355394