23910

Appears in sequences

• a(n) is a non-palindromic composite located between twin primes whose reverse, which is less than it, is also located between twin primes.at n=18A103741
• Averages of twin prime pairs which are a sum of averages of two consecutive twin prime pairs.at n=36A160916
• Triangle T(n,k), read by rows n>=0 with terms k=1..3^n, where row n lists the coefficients in the n-th iteration of (x+x^2+x^3).at n=48A166880
• Number of right triangles on an (n+1) X 5 grid.at n=29A189809
• Number of n-node rooted identity trees with thinning limbs and root outdegree (branching factor) 3.at n=15A245122
• Squarefree numbers n such that n^2 + 1 and n^2 - 1 are semiprime.at n=30A268697
• Counterexamples to a conjecture of Ramanujan about congruences related to the partition function.at n=39A340757