28049

Appears in sequences

• G.f.: (1-x)^5/((-1+4*x-3*x^2+x^3)*(1-3*x+x^2)*(-1+2*x)).at n=8A089932
• a(1)=1. a(n) = a(n-1) + sum of the triangular numbers which are among the first (n-1) terms of the sequence.at n=44A100963
• Numbers n such that the digits of sigma(n) are exactly the same (albeit in different order) as the digits of phi(n), in base 10.at n=30A175795
• Odd nonprimes n such that n+d+1 is prime for all divisors d of n.at n=39A187554
• Integers n such that n+2!, n+2!+3!, n+2!+3!+4!, n+2!+3!+4!+5!, n+2!+3!+4!+5!+6!, and n+2!+3!+4!+5!+6!+7! are all prime.at n=21A267123
• a(1) = 1; a(n+1) = Sum_{d|n} binomial(n,d) * a(d).at n=13A330017