6890625

Appears in sequences

• Squares of odd pentagonal numbers.at n=21A014769
• Odd abundant numbers whose abundance is odd.at n=18A156942
• Number of permutations of n elements divided by the number of quaternary heaps on n+1 elements.at n=38A273732
• a(n) = Product_{k=1..n} (binomial(k-1,4) + binomial(n-k,4)).at n=8A323497
• Odd abundant numbers k for which sigma(k) == 3 (mod 4).at n=10A325311
• Odd numbers k such that sigma(k) > 2*k and A003415(sigma(k)) < k, where A003415 is the arithmetic derivative, and sigma is the sum of divisors function.at n=7A347890