175594

Appears in sequences

• Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any horizontal or vertical neighbor, and containing the value n(n+1)/2-2.at n=33A211905
• a(n) is the first prime index where the gap between R(n), Riemann's prime counting function, and Pi(n), the exact prime counting function, is greater than n.at n=19A226473
• Semiprime numbers that are sandwiched between products of exactly 4 distinct primes (or tetraprimes).at n=15A375964
• a(n) = Sum_{k=0..n} 2^k * binomial(4*n+1,k) * binomial(4*n-k,n-k).at n=4A384366