18921

Appears in sequences

• a(n) = (3*n - 1)*(4*n - 1).at n=40A033578
• Centered 20-gonal (or icosagonal) numbers.at n=43A069133
• a(n) is the smallest multiple of n such that a(n) mod 100 = n and S(n)=n where S(n) is the sum of the base-ten digits of n, or 0 if no such a(n) exists.at n=20A075154
• Numbers n such that there are integers a < b with a^2+(a+1)^2+...+(n-1)^2 = (n+1)^2+(n+2)^2+...+b^2.at n=8A094552
• Numbers k such that 6*p(k)*p(k+1)*p(k+2)*p(k+3)*p(k+4)-1 and 6*p(k)*p(k+1)*p(k+2)*p(k+3)*p(k+4)+1 are twin primes with p(h) = h-th prime.at n=37A129310
• a(n) = (n^3 + 18*n^2 + 17*n + 6)/6.at n=43A143058
• Let S denote the palindromes in the language {0,1,2,...,n-1}*; a(n) = number of words of length 4 in the language SS.at n=20A187277
• a(n) is the smallest multiple of n such that a(n) ends with n and S(a(n))=n where S(m) is the sum of the base ten digits of m, or 0 if no such a(n) exists.at n=20A187924
• Number of (n+2) X (2+2) 0..3 arrays with every consecutive three elements in every row and column not having exactly two distinct values, and in every diagonal and antidiagonal having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=19A253019
• 25-gonal pyramidal numbers: a(n) = n*(n+1)*(23*n-20)/6.at n=17A256645
• Decimal representation of the x-axis, from the left edge to the origin, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 403", based on the 5-celled von Neumann neighborhood.at n=19A281846
• Number of n X 2 0..1 arrays with each 1 adjacent to 0, 2 or 4 king-move neighboring 1s.at n=9A296719
• Solution (a(n)) of the complementary equation a(n) = 2*a(n-1) - a(n-2) + b(n-2); see Comments.at n=45A305329
• Odd composite integers m such that A086902(m) == 7 (mod m).at n=40A338079
• a(n) = 20*binomial(n,6) + 2*binomial(n,3) + 1.at n=12A341704