a(n) = Product_{k=0..n} (5^k + 5^(n-k)).A369676a(n) = Product_{k=0..n} (5^k + 5^(n-k)).Terms a(0) =2a(1) =36a(2) =6760a(3) =14288400a(4) =331135220000External referencesoeis: A369676