21426

Appears in sequences

• a(n) = floor(n*phi^17), where phi is the golden ratio, A001622.at n=6A004932
• a(n) = round(n*phi^17), where phi is the golden ratio, A001622.at n=6A004952
• a(n) = Sum_{k=0..n} T(n, k)*T(n, n+k), T given by A027960.at n=9A027984
• Numbers which are the sum of their proper divisors containing the digit 7.at n=26A059466
• Number of two-rowed partitions of length 5.at n=28A070558
• Indices of primes in sequence defined by A(0) = 83, A(n) = 10*A(n-1) - 7 for n > 0.at n=20A101062
• Triangle, read by rows, where T(n,k) = n*T(n-1,k-1) + T(n-1,k-2) for n>0 and k>1, with T(n,0) = T(n-1,n-1) and T(n,1) = n*T(n-1,0) for n>0 and T(0,0) = 1.at n=39A132005
• Number of 3-stack sortable permutations on n letters.at n=7A134664
• 6 times centered hexagonal numbers: 18*n*(n+1) + 6.at n=34A164016
• (A192533)/2.at n=36A192534
• Numbers which do not reach zero under either of the iterations: x -> floor(sqrt(x)) * (x - floor(sqrt(x))^2) or y -> ceiling(sqrt(y)) * (ceiling(sqrt(y))^2 - y).at n=26A219963
• Number of length n+4 0..5 arrays with every five consecutive terms having two times the sum of some three elements equal to three times the sum of the remaining two.at n=12A248984