20474

Appears in sequences

• a(n) = binomial(n+5,4) - 1.at n=23A063258
• G.f.: (1+3*x+2*x^2)/((1-x)*(1-2*x^2)).at n=23A063757
• Prime(a(n)) + ... + prime(a(n)+3) is a square = A051395(n)^2.at n=22A072849
• a(n) = a(n-1) + 2*a(n-4) - 2*a(n-5) for n >= 5, where a(0) = 2, a(1) = 4, a(2) = 6, a(3) = 8, a(4) = 10.at n=45A288732
• Even composite integers m such that U(m)^2 == 1 (mod m) and V(m) == 7 (mod m), where U(m)=A004187(m) and V(m)=A056854(m) are the m-th generalized Lucas and Pell-Lucas numbers of parameters a=7 and b=1, respectively.at n=34A337782