25721

Appears in sequences

• Numbers k such that the concatenation of k with 4*k gives a square.at n=0A115535
• Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in a 10001-11111-00100 pattern in any orientation.at n=13A147385
• Number of permutations of length n that avoid the patterns 1243 and 2431.at n=8A165534
• Number of ordered triples (w,x,y) with all terms in {-n,...-1,1,...,n} and 2w+x+y>2.at n=19A211619
• Nonsemiprimes in A306097 = A121707 \ A267999.at n=35A321488
• a(n) = Sum_{k=1..n} k * lcm(k,n).at n=16A344508