21393

Appears in sequences

• a(n) = [ a(n-1)/a(1) ] + [ a(n-1)/a(2) ] + ... + [ a(n-1)/a(n-1) ] for n >= 3, with initial terms 2,1.at n=11A022874
• Number of reversible string structures with n beads using exactly five different colors.at n=9A056329
• Let R(i,j) be the rectangle with antidiagonals 1; 2,3; 4,5,6; ...; the n-th Lucas number is in antidiagonal a(n).at n=40A057045
• Binomial transform of [1, 2, 3, 4, 0, 0, 0, ...].at n=32A139488
• a(n) = floor(6^n/(3+sqrt(3))^n).at n=42A240735
• Triangle read by rows: T(n,k) = number of reversible string structures of length n using exactly k different symbols.at n=49A284949
• Solution of the complementary equation a(n) = 2*a(n-1) - b(n-2), where a(0) = 3, a(1) = 5, b(0) = 1, b(1) = 2, and (a(n)) and (b(n)) are increasing complementary sequences.at n=14A295060
• Integers that concatenate 3 counts: the number of terms in the sequence so far, the number of primes in the sequence so far, the number of digits in the sequence so far, with a(1)= 113. The sequence is always extended with the smallest available integer not leading to a contradiction or a dead end.at n=20A309617
• Number of distinct characteristic polynomials for 3 X 3 matrices with entries from {0, 1, ..., n}.at n=4A366551