21909

Appears in sequences

• Number of partitions of n into parts not of the form 21k, 21k+8 or 21k-8. Also number of partitions with at most 7 parts of size 1 and differences between parts at distance 9 are greater than 1.at n=38A035986
• a(n) = a(n-1)^2 + n, with a(0)=0.at n=5A098152
• a(1)=3; for n > 1, a(n) = 1 + a(n-1) + gcd( a(n-1)*(a(n-1)+2), A073829(a(n-1)) ).at n=36A167053
• Total number of ON cells in the "Ulam-Warburton" two-dimensional cellular automaton of A147562 after A048645(n) generations.at n=31A255264
• Partial sums of A299037.at n=50A299767
• Number of meanders of length n with Motzkin-steps avoiding the consecutive steps UD and HH.at n=14A329675
• Floor of area of triangle whose sides are consecutive Ulam numbers (A002858).at n=43A330909
• a(n) is the minimum sum of a nonnegative integer 4-tuple that takes n moves to reach a 0 component, where a move picks two components, subtracts the smaller from the larger, and doubles the smaller.at n=12A383586