19775

Appears in sequences

• Number of monosubstituted alkanes C(n-1)H(2n-1)-X with n-1 carbon atoms that are not stereoisomers.at n=21A000621
• a(0) = 1, a(n) = 13*n^2 + 2 for n>0.at n=39A010004
• Numbers k such that k = prime(P) + pi(P), where P is product of digits of k.at n=5A164324
• Triangle read by rows: T(n,k) is the number of partitions of the set {1,2,...,n} having k adjacent blocks of size 3, i.e., blocks of the form (i,i+1,i+2) (0 <= k <= floor(n/3)).at n=18A184176
• Number of set partitions of {1,2,...,n} having no blocks of the form {i,i+1,i+2}.at n=9A184177
• Number of preferential arrangements of n labeled elements with repetitions allowed.at n=6A213048
• a(n) = Sum_{i=1..n, j=1..n, gcd(i,j)=2} (n+1-i)*(n+1-j).at n=25A331761