491520

Appears in sequences

• Generalized Euler phi function (for p=2).at n=19A003473
• Theta series of D*_15 lattice.at n=23A022068
• One eighth of octo-factorial numbers.at n=4A034976
• a(n) = n*2^n.at n=15A036289
• a(1) = 5, a(n) = sigma(a(n-1)).at n=13A051572
• a(n) = n*omega(n)^n where omega(n) is the number of distinct prime divisors of n.at n=14A061340
• n*bigomega(n)^n, where bigomega(n) is the number of prime divisors of n, counted with multiplicity.at n=14A061452
• Product of nonzero digits of A066555(n).at n=8A066585
• 17-almost primes (generalization of semiprimes).at n=6A069278
• Numbers of the form 5*2^n or 5*3*2^n; a(n) = 5*A029744(n).at n=32A070004
• Binary expansion is 1xx100...0 where xx = 00 or 11.at n=31A070876
• Smallest k > n such that there are exactly n pairs (x,y) (1 <= x <= y <= k) solutions of the equation: phi(xy)=sigma(x)+sigma(y).at n=39A071780
• Expansion of (1-3x+4x^2-3x^3+x^4)/(1-2x)^2.at n=17A084861
• Numbers n such that phi(n) = 2^bigomega(n).at n=32A089693
• Number of subsets of {1,.., n} containing at least one square.at n=18A089888
• Inverse binomial transform of n*Pell(n).at n=30A093968
• Expansion of (1 - 4*x + 6*x^2)/(1 - 2*x)^2.at n=16A097064
• a(n) = n*(n-1)/2 * 2^(n*(n-1)/2).at n=5A103904
• a(n) = 15*2^n.at n=15A110286
• a(n) is the number of divisors of the concatenation of 2178 with itself n times.at n=17A110753