57291

Appears in sequences

• Numbers k such that 285*2^k + 1 is prime.at n=29A053359
• Triangular numbers such that the product of digits is also a (positive) triangular number.at n=19A069077
• Numbers k such that sigma(k-phi(k)) = phi(k).at n=16A070170
• G.f.: x*(1 - x + x^2)/((1-x)^2 * (1 - x - x^2)).at n=21A104161
• Concatenation of triangular number k and its 10's complement is prime.at n=21A108970
• Triangular numbers T such that T+10 is the next prime after T.at n=10A129540
• Triangular numbers for which the product of the digits is a nonzero hexagonal number.at n=9A185211