21542

Appears in sequences

• Coordination sequence for MgCu2, Cu position.at n=37A009930
• Integers n > 10553 such that the 'Reverse and Add!' trajectory of n joins the trajectory of 10553.at n=18A063061
• Semiprimes (A001358) whose digit reversal is a pentagonal number (A000326).at n=28A115708
• Number of permutations of length n that avoid the patterns 321, 1342, 4123.at n=16A116714
• Least k such that prime(n) is the smallest prime p for which k^2 + p^2 is also prime, or 0 if none.at n=60A263466
• Number of n X 2 0..2 arrays with no element unequal to a strict majority of its horizontal and vertical neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.at n=12A279851
• a(n) is the largest number whose sixth power is an n-digit sixth power which has the maximum sum of digits (A373994(n)).at n=25A380193
• Alternating sum of the numbers in the trajectory of n for the 3x+1 problem.at n=53A386437