42626

Appears in sequences

• a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n+1-k), where k = [ (n+1)/2 ], s = A001950 (upper Wythoff sequence).at n=40A024689
• a(n) = (A114043(n) - 1)/2.at n=22A115005
• First of 3 or more consecutive integers with equal values of phi(phi(n)).at n=28A167767
• Number of permutations of [n] avoiding {1324, 2341, 3421}.at n=11A294800