131220

Appears in sequences

• a(n) = Sum_{k=0..2n} (k+1) * A025177(n, k).at n=9A027261
• Triangle whose (i,j)-th entry is binomial(i,j)*4^(i-j)*9^j.at n=19A038239
• Triangle whose (i,j)-th entry is binomial(i,j)*9^(i-j)*4^j.at n=16A038294
• Numbers divisible by the 4th power of the sum of their digits in base 10.at n=14A072083
• Let f(n) = fraction of digits that are nonzero when n is written in base 2 and g(n) the same fraction for base 3. Let h(n) = max {f(n), g(n)}. Sequence gives n for which h(n) sets a new low record.at n=10A078415
• Factorial expansions of the entries in A085216.at n=31A085218
• Begin with first number 15. Add the digits of the first number to give the second; the first number multiplied by the second gives the third. The third number becomes the first in a new "set" of three.at n=8A111298
• a(n) = 9^n * n*(n+1).at n=4A116176
• a(n) = 3*a(n-1), with a(1) = 20.at n=8A116530
• a(n) = (n^3 - n^2)*3^n.at n=5A128986
• Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly 1 local maximum.at n=8A159715
• Totally multiplicative sequence with a(p) = 9*(p+2) for prime p.at n=41A167310
• Totally multiplicative sequence with a(p) = 9*(p+3) for prime p.at n=17A167328
• Define the array k(n,x) = number of m such that tau(gcd(n,m)) is x where m runs from 1 to n. Also define h(n,x) = Sum_{d|n : tau(d) = x} d. The sequence contains numbers n such that k(n,x)*x = h(n,x) has at least one solution x.at n=20A197099
• Triangle read by rows: terms T(n,k) of a binomial decomposition of n^n as Sum(k=0..n)T(n,k).at n=24A244135
• a(0) = 1; 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) + Sum_{i=1..n} a(i).at n=31A250305
• Product_{d|n, d<n} A276086(phi(d)), where A276086 is primorial base exp-function, and phi is Euler totient function.at n=39A353564
• Numbers whose prime factors counted with multiplicity satisfy: (maximum) - (minimum) = (mean).at n=36A362268
• Number of integer grid points on the circle around (0,0) with radius A088959(n).at n=26A365620
• a(n) = Product_{d|n} A276086(d)^A349394(n/d).at n=19A380459