722211

Appears in sequences

• Numbers k such that k and k^2 use only the digits 1, 2, 5, 7 and 8.at n=17A137008
• G.f.: A(x) satisfies 1 = Sum_{n>=0} Product_{k=3*n..4*n-1} ( (1+x)^k - A(x) ).at n=5A338183