218453

Properties

Appears in sequences

• a(n) = a(n-1) + 2*a(n-2), a(0)=2, a(1)=3.at n=17A048573
• a(n+1) = smallest number not containing any digits of a(n), working in base 4.at n=21A049548
• a(n) = 4*a(n-1) + 1 with a(0) = 3.at n=8A072197
• Numbers k such that A081252(m)/m^2 has a local maximum for m = k.at n=17A081254
• a(n) is the index of F(n+1) at the unique occurrence of the ordered pair of reversed consecutive terms (F(n+1),F(n)) in Stern's diatomic sequence A002487, where F(k) denotes the k-th term of the Fibonacci sequence A000045.at n=17A086893
• a(n) is the least prime p such that exponent of highest power of 2 dividing 3p+1 equals n.at n=16A087964
• a(n) = 4*a(n-2) + 1 with a(1) = 0, a(2) = 3.at n=17A096773
• Least primes of the form k 4^n + (4^n-1)/3.at n=8A127598
• A generalized Jacobsthal sequence.at n=16A159290
• Locations of row maxima in "crushed" version of Stern's diatomic array.at n=33A169969
• Numbers of form 4^(3*k+l+1)/9 - 4^l/9 - 1/3 or 2*4^(3*k+l+2)/9 - 2*4^l/9 - 1/3, k,l>=0.at n=37A172143
• Odd numbers producing exactly 3 odd numbers in the Collatz (3x+1) iteration.at n=24A198584
• Least n such that L(n)<-1 and L(n)<L(n-1), where L(k) means the least root of the polynomial p(k,x) defined at A206284, and a(1)=13.at n=7A206444
• Triangle read by rows: T(n,k) = number of squares and rectangles of area 2^(k-1) after 2^n stages in the toothpick structure of A139250, divided by 4, n>=1, k>=1, assuming the toothpicks have length 2.at n=56A211019
• Odd numbers producing 3 decreasing odd numbers in the Collatz (3x+1) iteration.at n=21A228872
• Rectangular array with all start numbers Mo(n, k), k >= 1, for the Collatz operation ud^(2*n-1), n >= 1, ending in an odd number, read by antidiagonals.at n=44A238476
• Primes p such that the greatest prime factor of 3*p+1 is at most 5.at n=11A276827
• a(n) = 4*a(n-2)+1 with initial terms 1,3,7.at n=17A283323
• Numbers of the form (2^(2*j + 6*k + 5) - 2^(2*j + 1) - 3)/9, with j,k >= 0.at n=15A342815
• An array A of the positive odd numbers, read by antidiagonals upwards, giving the present triangle T.at n=53A347834