23161

Appears in sequences

• a(n) is the concatenation of n and 7n.at n=22A009441
• Numbers k such that sigma(k) = sigma(k+10).at n=27A015880
• Numbers m such that the factorizations of m..m+4 have the same number of primes (including multiplicities).at n=15A045941
• Count of interior bounded regions in a regular 2n-sided polygon dissected by all diagonals parallel to sides.at n=17A165217
• A triangular sequence:f(n)=Sum[StirlingS2[n, k], {k, 1, n}];t(n,m)=Binomial[n, m]*f(m + 1)*f(n - m + 1)-Binomial[n,0]*f(1)*f(n+1)+1.at n=31A174639
• A triangular sequence:f(n)=Sum[StirlingS2[n, k], {k, 1, n}];t(n,m)=Binomial[n, m]*f(m + 1)*f(n - m + 1)-Binomial[n,0]*f(1)*f(n+1)+1.at n=32A174639
• Numbers n such that the digits of sigma(n) are exactly the same (albeit in different order) as the digits of phi(n), in base 10.at n=26A175795
• Number of emergent parts in all partitions of n.at n=37A182699
• Number of (n+1) X (n+1) 0..3 symmetric matrices containing all values 0..3 with every 2 X 2 subblock having one, two or three distinct values, and new values 0..3 introduced in lower triangle row major order.at n=2A210819
• Number of ordered triples (w,x,y) with all terms in {1,...,n} and 2*w^2 < x^2 + y^2.at n=34A211800
• Numbers n such that n, n + 1, n + 2, n + 3 and n + 4 are products of exactly three primes.at n=14A268588
• Number of lattice paths from (0,0) to (n,n) that consist of steps (h,v) with h, v prime or one.at n=10A308240
• The number of tiles inside a regular n-gon created by diagonals that run from each of the n vertices to the n-2 midpoints of opposite edges.at n=17A320422