51358

Appears in sequences

• Numbers n for which there are exactly seven k such that n = k + (product of nonzero digits of k).at n=9A096928
• Numbers n such that sopfr(n-1) | (n+sopfr(n+1)) and sopfr(n+1) | (n+sopfr(n-1)), where sopfr = A001414 (sum of prime factors with repetition).at n=5A196994
• Start with a(0) = a(1) = 1. If a(n) = n is the rightmost term defined so far, let a(m) = m := n + a(n-1). If the terms between a(n) and a(m) are undefined, let a(n+1) = a(n) + a(m) and if m > n+1, a(m-1) = a(n+1) + a(m).at n=21A333375
• Semiprime numbers that are sandwiched between products of exactly 4 distinct primes (or tetraprimes).at n=1A375964