128814

Appears in sequences

• a(n) = 17 + floor( (1 + Sum_{j=0..n-1} a(j))/2 ).at n=22A120143
• The number of reversible primes (palindromic or emirps) by increasing permissible leading digit and by length.at n=31A220344
• Number of emirps of length ceiling(n/4)+1 and leading digit 1, 3, 7 or 9 (in sequence).at n=27A220349
• Number of unbranched tri-4-catafusenes under the symmetry point group C_{2v} as a function of the number of hexagons (see Cyvin et al. (1996) for precise definition).at n=20A323939
• a(n) is the number of solutions to x^y == y^x (mod p) where 0 < x,y <= p^2 - p and p is the n-th prime.at n=13A355069