12597120domain: NAppears in sequencesa(n) = 3^(n^2+2n+1)*Product_{j=1..n} (9^j-1).at n=2A092301Greatest common divisor of multiperfect numbers and their totient.at n=34A098204Number of permutations of 5 indistinguishable copies of 1..n arranged in a circle with exactly 1 local maximum.at n=7A159733