19980

Appears in sequences

• Let [n] = {0,...,n-1}; a(n) is number of functions f:[n] -> [n] for which there exists an injection g:[n] -> [n+1] such that for j with 0 <= j < n, either g(j) = f(j) or g(j) = f(j)+1.at n=5A028498
• Triangle of coefficients of certain polynomials (exponents in decreasing order).at n=23A046757
• a(n) = (largest prime < 10^n) + (smallest prime > 10^n).at n=3A097515
• a(n) = 9973*n + 10007.at n=1A101442
• Numbers k such that if you subtract k-reversed from k you get a natural number with the same digits as k.at n=7A121969
• Triangle read by rows: T(n,k) (n >= 2, k >= 1) is the number of non-crossing connected graphs on n nodes on a circle such that the distance from a fixed node (root) to the next node is k. Rows are indexed 2,3,4,...; columns are indexed 1,2,3, ... .at n=22A143018
• Sum of the root degrees over all non-crossing connected graphs on n nodes on a circle (by root we mean a distinguished node).at n=5A143023
• a(n) = Sum_{k=0..n} (n+k+2)!/((n-k)!*k!*2^k).at n=4A144513
• a(n) = 1000*n - 20.at n=19A157515
• Number of ways to place 3 nonattacking knights on a 3 X n board.at n=17A172212
• Numbers n, not relatively prime to 10, such that the decimal form of the period of 1/n is prime.at n=55A179192
• Number of distinct solutions of sum{i=1..3}(x(2i-1)*x(2i)) = 0 (mod n), with x() only in 1..n-1.at n=15A180774
• Number of ordered triples (w,x,y) with all terms in {1,...,n} and w^3 >= x^3 + y^3.at n=41A211651
• Number of partitions of 3 copies of n into distinct parts.at n=20A258281
• Numbers such that the decimal digits of sigma(n) are a permutation of those of sigma(n)-n.at n=11A277114
• Decimal representation of the diagonal from the corner to the origin of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 260", based on the 5-celled von Neumann neighborhood.at n=42A287285
• Numbers n with the property that k*n and (k+1)*n have a common nonzero digit for all k.at n=27A308466
• Number T(n,k) of parts in all proper k-times partitions of n; triangle T(n,k), n >= 1, 0 <= k <= n-1, read by rows.at n=44A327631
• Exponential (2,4)-perfect numbers: numbers m such that esigma(esigma(m)) = 4m, where esigma(m) is the sum of exponential divisors of m (A051377).at n=9A328133
• a(n) is the smallest number that can be partitioned into n ways as the sum of two Moran numbers.at n=38A337862