34047

Appears in sequences

• Number of immersions of the oriented circle into the unoriented plane with n double points.at n=7A008982
• COMPOSE primes with primes.at n=6A030278
• Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 17.at n=27A051982
• Heptagonal numbers for which the sum of the digits is also a heptagonal number.at n=29A117650
• A general recursion triangle with third part a power triangle:m=2; Power triangle: f(n,k,m)=If[n*k*(n - k) == 0, 1, n^m - (k^m + (n - k)^m)]; Recursion: A(n,k,m)=(m*(n - k) + 1)*A(n - 1, k - 1, m) + (m*k + 1)*A(n - 1, k, m) + m*f(n, k, m)*A(n - 2, k - 1, m).at n=23A157629
• A general recursion triangle with third part a power triangle:m=2; Power triangle: f(n,k,m)=If[n*k*(n - k) == 0, 1, n^m - (k^m + (n - k)^m)]; Recursion: A(n,k,m)=(m*(n - k) + 1)*A(n - 1, k - 1, m) + (m*k + 1)*A(n - 1, k, m) + m*f(n, k, m)*A(n - 2, k - 1, m).at n=25A157629
• The third left hand column of triangle A167552.at n=11A167555
• Monotonic ordering of set S generated by these rules: if x and y are in S then x^2+y^2+xy is in S, and 1 is in S.at n=12A192535
• Triangular array read by rows: row n shows the coefficients of the polynomial p(x,n) constructed as in Comments; these polynomials form a strong divisibility sequence.at n=37A328644
• Number of vertices in an equilateral triangle "frame" of size n (see Comments in A328526 for definition).at n=16A333031