18952

Appears in sequences

• Numbers k such that h(k) = h(k-1) + h(k-2), where h(k) = A006577(k) + 1 is the length of the sequence {k, f(k), f(f(k)), ...., 1} in the Collatz (or 3x + 1) problem. (The earliest "1" is meant.)at n=36A078418
• G.f.: x*(1+x+x^2)*(1+6*x+8*x^2+4*x^3-x^4)/((1+x)^2*(1-x)^4).at n=21A147691
• Number of fixed polyominoes in equilibrium; a fixed polyomino is in equilibrium when its center of mass is vertically aligned with a cell with minimal coordinate.at n=12A171579
• Number of strictly increasing arrangements of 4 nonzero numbers in -(n+2)..(n+2) with sum zero.at n=43A188123
• Sophie Germain 5-almost primes.at n=38A211162
• Number of length n+2 0..5 arrays with the sum of the maximum minus twice the median plus the minimum of adjacent triples multiplied by some arrangement of +-1 equal to zero.at n=3A251425
• T(n,k)=Number of length n+2 0..k arrays with the sum of the maximum minus twice the median plus the minimum of adjacent triples multiplied by some arrangement of +-1 equal to zero.at n=31A251428
• Number of length 4+2 0..n arrays with the sum of the maximum minus twice the median plus the minimum of adjacent triples multiplied by some arrangement of +-1 equal to zero.at n=4A251431
• Numbers n such that the sum of the inverse of the exponents in the binary expansion of 2n is the inverse of an integer.at n=26A272034
• Numbers n such that Bernoulli number B_{n} has denominator 1410.at n=22A272369
• a(n) is the last number in the (2n+1)-element alternating sequence of x/2 and (3x+1) iterations starting with A277215(n).at n=6A277874
• a(n) = 2*F(n-1) + 2*F(n-3) + 10*F(n-5) + 9*F(n-8) where n >= 8 and F = A000045.at n=12A280932
• a(n) = a(n-1) + a(n-2) - n*a(floor(n/2)), where a(0) = 1, a(1) = 2, a(2) = 3.at n=17A298401
• a(n) = 36*n^2 - 4*n (n>=1).at n=22A304380
• a(1) = 102735, a(n) = prime(n-1)*a(n-1) but products that are not in A010784 are first reduced as in A320486 (see comments); continue until zero is reached.at n=27A321149
• Records in A333549.at n=35A333550
• a(n) = Sum_{j=1..n} Sum_{k=1..n} tau(j*k).at n=39A372674
• a(n) is the number of terms less than A276086(n) in the range of A276086, where A276086 is the primorial base exp-function.at n=57A376411
• Expansion of (1+2*x-x^3) / (1-x-5*x^2+x^3+2*x^4).at n=10A384641