87087

Appears in sequences

• Odd integers m such that phi(m) | sigma(m).at n=26A015715
• a(n) = s(n+3)/3, where s is A024737.at n=10A024738
• a(n) = Sum_{i=1..floor((n+2)/4)} a(2i-1)*a(n-2i+1), with a(1)=3 and a(2)=a(3)=1.at n=12A024958
• Numbers k that, when expressed in base 4 and then interpreted in base 9, give a multiple of k.at n=27A062925
• Numbers n such that the arithmetic, geometric and harmonic means of phi(n) and sigma(n) are all integers.at n=30A065146
• Numbers k such that sigma(k) = 4*phi(k).at n=23A068390
• Numbers k such that sigma(k) = phi(k*bigomega(k)).at n=27A068400
• Numbers k such that both k and 2*k are balanced numbers (A020492).at n=39A076375
• Numbers k such that k, 2*k and 4*k are balanced numbers (A020492).at n=20A076376
• Numbers k such that k, 2*k, 4*k and 8*k are balanced numbers (A020492).at n=7A076377
• Numbers n such that the middle coefficient of the cyclotomic polynomial Phi_n(x) has a value not obtained for any smaller n.at n=39A095877
• a(n) = Catalan(n+1)*Bell(n).at n=6A289680
• Integers n such that sigma(n)/phi(n) is a perfect square.at n=42A293391
• Number of partitions of n such that 4*(greatest part) >= (number of parts).at n=44A347868