19500

Appears in sequences

• Even 9-gonal (or enneagonal) numbers.at n=37A028992
• a(n) = (2*n+1)*(7*n+1).at n=37A033572
• Sums of 4 distinct powers of 5.at n=34A038476
• Triangle of coefficients of certain Sheffer-polynomials.at n=17A048870
• Number of polybricks: number of ways to arrange n 1 X 2 "bricks" in a wall (see illustrations).at n=8A057973
• Enneagonal numbers for which the product of the digits is also an enneagonal number.at n=22A117052
• Number of permutations of n distinct letters (ABCD...) each of which appears 5 times and having n-2 fixed points.at n=39A123296
• a(n) = (n-1)*(n+4)*(n+6)/6 for n > 1, a(1)=1.at n=45A137742
• Sequence generated from the 5/5Z addition table considered as a matrix.at n=4A140044
• a(n) = Sum_{d|n} Moebius(n/d)*d^(b-1)/phi(n) for b = 5.at n=24A160891
• 1-sequence of reduction of the upper Wythoff sequence by x^2 -> x+1.at n=13A192303
• Molecular topological indices of the graph join C_n + C_n of cycle graphs.at n=12A192848
• a(n) = v(n+1)/v(n), where v = A203482.at n=2A203483
• Numbers k such that k divides 1 + Sum_{j=1..k} prime(j)^9.at n=16A232964
• a(0) = 3; a(n+1) is the smallest number not in the sequence such that a(n+1) - Sum_{i=1..n} a(i) divides a(n+1) - Product_{i=1..n} a(i).at n=25A254344
• a(n) = n*(7*n - 5)*(49*n^2 - 35*n - 10)/8.at n=5A264894
• a(n) = (n-4)*(n+1)*(n+3)/6.at n=45A275874
• Numbers k such that k mod phi(k) = lambda(k).at n=27A290184
• L.g.f.: Sum_{n>=1} x^((2*n-1)^2) / ( (2*n-1) * (1 - x^(2*n))^(2*n-1) ).at n=62A293598
• a(n) = Product_{d|n, d>1} prime(A304101(d)-1).at n=69A304104