20499

Appears in sequences

• First of three consecutive Ulam numbers (A002858) in arithmetic progression with difference 22.at n=15A068856
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (-1, 1, 0), (0, 0, -1), (0, 1, 1), (1, 0, 0)}.at n=8A150175
• Numbers m such that m*reversal(m) contains every decimal digit exactly once.at n=5A178929
• Density of twin primes: the number of primes that are twin primes among the first 10^n primes.at n=4A273497
• Ulam numbers k such that k/3 is also an Ulam number.at n=32A287212
• Expansion of e.g.f. Product_{k>=1} (1 + x^k/k!)^prime(k).at n=7A371308