18422

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=30A078418
• Numbers n such that h(n) = 2 h(n-1) where h(n) is the length of the sequence {n, f(n), f(f(n)), ...., 1} in the Collatz (or 3x + 1) problem. (The earliest "1" is meant.)at n=34A078419
• a(n)*a(n+3) - a(n+1)*a(n+2) = 5, given a(0)=a(1)=1, a(2)=2.at n=10A080873
• Numbers k > 0 such that k^2 is a centered triangular number.at n=9A129445
• a(n) = 10*a(n-1) - a(n-2).at n=5A140781
• Even composites in A145832 with at least three distinct prime factors.at n=6A145916
• Number of n X 3 1..2 arrays containing at least one of each value, all equal values connected, rows considered as a single number in nondecreasing order, and columns considered as a single number in nonincreasing order.at n=45A166830
• Smallest number m such that A176352(m) = n.at n=52A218454
• Number of partitions p of n such that median(p) = multiplicity(max(p)).at n=44A240209
• Row sums of the array A274196, defined by g(n,k) = 1 for n >= 0; g(n,k) = 0 if k > n; g(n,k) = g(n-1,k-1) + g(n-1,4k) for n > 0, k > 1.at n=45A274197
• Numbers k such that 24*k-1 has at least three factors 7 and the partition function evaluated at k has at least the same number of factors 7 as 24*k-1.at n=22A340957
• Triangle read by rows. T(n, k) = A356265(n, k) + A357078(n, k) for 0 <= k <= n.at n=48A357079
• Total number of blocks in all set partitions of [n] such that each element is contained in a block whose index parity coincides with the parity of the element.at n=11A364267
• Number of integer compositions of n whose leaders of weakly increasing runs are identical.at n=17A374631