68797

Appears in sequences

• a(n) = 9*a(n-1) + a(n-2) for n>1; a(0) = a(1) = 1.at n=6A015455
• a(n)=a(n-1)+a(n-2)-a(n-4)+a(n-5).at n=21A021014
• Number of partitions of n*(n+1)/2 with at most four parts that can be obtained from grouping (with parentheses) a permutation of the sum 1+2+...+n.at n=20A160438
• Main diagonal of Ludic array A255127 (and A255129): a(n) = A255127(n,n).at n=38A255410
• Semiprimes k such that k+4, k+6, k+9, k+10 and k+14 are also semiprimes.at n=20A360666