72721

Appears in sequences

• Numbers k such that k * (k + 7) is the concatenation of a number m with itself.at n=7A116291
• Expansion of g.f. x*(1 - x)*(1 + x)/((x^2 + 3*x + 1)*(x^2 - 4*x + 1)).at n=10A171067
• The least number s having exactly n fours in the continued fraction of sqrt(s).at n=29A206584
• Numbers n such that n, n + 1, n + 2, n + 3 and n + 4 are products of exactly three primes.at n=38A268588
• a(n) = (n^2 - n + 2) * (5*n^2 - 5*n + 2) / 4.at n=15A380353