42009

Appears in sequences

• a(n) = (10n+1)*(10n+9).at n=20A001535
• Integers that are Rhonda numbers to base 6.at n=11A100969
• Number of binary words of length n with properties that there is no pair of adjacent 1's and no subword of the form X^4 for any string X.at n=29A170877
• G.f. A(x) satisfies A(x) = 1/( 1 - x*(A(x) + A(-x))*(A(x) + A(w*x) + A(w^2*x))/6 ), where w = exp(2*Pi*i/3).at n=13A385699