61969

Appears in sequences

• a(n) = n-th multiple of n with digit sum n.at n=30A082260
• Expansion of 1/(1 - x - x^3 - x^5 - x^7).at n=25A117760
• Number of (w,x,y,z) with all terms in {1,...,n} and w*x-y*z<=n.at n=18A212109
• a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/4)} binomial(n,4*k+1) * a(k).at n=17A352904
• G.f. A(x) satisfies 1/x = Sum_{n=-oo..+oo} A(x)^(2*n) * (A(x)^n + 2)^(2*n+1).at n=8A378572