127680

Appears in sequences

• Numbers k such that k-1, k+1, k^2+1 and k^4+1 are all prime numbers.at n=11A070156
• Numbers k such that (k-1, k+1) and (k/2-1, k/2+1) are both pairs of twin primes.at n=17A076504
• Numbers that can be expressed as the difference of the squares of primes in exactly nine distinct ways.at n=17A092005
• Consider a Pythagorean triangle with sides a=u^2-v^2, b=2uv, c=u^2+v^2. The sequence is the area of the triangle when v=2, u=3,4,5,...at n=37A096382
• Area of the Pythagorean triangle a = u^2 - v^2 (cf. A096382) when u=3, v=4,4,5,...at n=31A096383
• A triangular sequence recursion: A(n,k)=A(n - 1, k - 1) + A(n - 1, k) + (-12 + 5 n) (-9 + 5 n)*A(n - 2, k - 1).at n=17A153878
• A triangular sequence recursion: A(n,k)=A(n - 1, k - 1) + A(n - 1, k) + (-12 + 5 n) (-9 + 5 n)*A(n - 2, k - 1).at n=18A153878
• Sequence gives the Poincaré series [or Poincare series] of an ordinal Hodge algebra, or algebra with straightening law, for a ring that the braid group on four strands acts on. It is Cohen-Macaulay.at n=23A156231
• Twin prime averages which are also the sum of the divisors of a triangular number.at n=31A166162
• Numbers which are the area of exactly three Pythagorean triangles.at n=16A177021
• Numbers other than prime powers divisible by the sum of the squares of their prime divisors.at n=10A190882
• Triangle of coefficients of a sequence of polynomials related to the enumeration of linear labeled rooted trees.at n=19A194649
• Triangle by rows T(n,k), showing the number of meanders with length (n+1)*6 and containing (k+1)*6 Ls and (n-k)*6 Rs, where Ls and Rs denote arcs of equal length and a central angle of 60 degrees which are positively or negatively oriented.at n=12A197655
• Numbers n such that there are three distinct triples (k, k+n, k+2n) of squares.at n=7A222154
• Triangle read by rows, k!*S_4(n, k) where S_m(n, k) are the Stirling-Frobenius subset numbers of order m; n >= 0, k >= 0.at n=17A225473
• Take apart the sides of each of the integer-sided triangles with perimeter n (at their vertices) and rearrange them orthogonally in 3-space so that their endpoints coincide at a single point. a(n) is the total volume of all rectangular prisms enclosed in this way.at n=44A308233
• Number T(n,k) of multisets of nonempty words with a total of n letters over k-ary alphabet such that for k>0 the k-th letter occurs at least once and within each word every letter of the alphabet is at least as frequent as the subsequent alphabet letter; triangle T(n,k), n>=0, 0<=k<=n, read by rows.at n=51A319495
• Numbers m such that the equation m = k*sigma(k) has more than one solution.at n=9A337873
• a(n) is the least x such that x-1 and x+1 are prime and there are exactly n primes of the form x-1+t or x+1+t where t divides x.at n=43A340170
• Expansion of e.g.f. Sum_{k>=0} x^k / (1 - k*x^k/k!).at n=8A356667