1076000

Appears in sequences

• Consider sequence of fractions A066657/A066658 produced by ratios of terms in A066720; let m = smallest integer such that all fractions 1/n, 2/n, ..., (n-1)/n have appeared when we reach A066720(m) = k; sequence gives values of k; set a(n) = -1 if some fraction i/n never appears.at n=24A066848
• Consider sequence of fractions A066657/A066658 produced by ratios of terms in A066720; let m = smallest integer such that all fractions 1/n, 2/n, ..., (n-1)/n have appeared when we reach A066720(m) = k; sequence gives values of k; set a(n) = -1 if some fraction i/n never appears.at n=49A066848
• Numbers k such that k and k^2 use only the digits 0, 1, 5, 6 and 7.at n=23A136869
• a(n) = 100^[n/10] + 2*n*10^[n/10]: inspired by Engel expansion of Pi.at n=38A137507
• G.f. A(x) satisfies 2 = Sum_{n=-oo..+oo} x^(4*n) * (1 - x^n)^(4*n) * A(x)^n.at n=21A379196