3145727

Appears in sequences

• a(0) = 1; a(n) = 3*2^n - 1, for n > 0.at n=20A052940
• a(2n) = 2*2^n - 1, a(2n+1) = 3*2^n - 1.at n=41A052955
• a(0) = 0; for n > 0, a(n) = 3*2^(n-1) - 1.at n=21A055010
• Variation on Ulam numbers: a(1) = 1; a(2) = 2; for n>2, a(n) = smallest (n odd) or largest (n even) number > a(n-1) that is a unique sum of two distinct earlier terms.at n=41A081026
• a(0) = 1; for n > 0, a(n) = 3*2^(n-1) - 1.at n=21A083329
• Add 1, double, add 1, double, etc.at n=41A083416
• Expansion of g.f.: (3+x+2*x^2-2*x^3)/((1-2*x)*(1+x^2)).at n=20A100720
• Smallest semiprime with Hamming weight n (i.e., smallest semiprime with exactly n ones when written in binary), or -1 if no such number exists.at n=20A102029
• Slater-Velez permutation sequence of the 2nd kind.at n=40A129198
• a(n) = 3*2^n - 1.at n=20A153893
• Numbers of the form i*4^j-1 (i=1..3, j >= 0).at n=32A180516
• a(n) = 3*4^n-1.at n=10A198693
• a(n) = a(n-1) + 2*a(n-2) with n>1, a(0)=2, a(1)=7.at n=20A201630
• Numbers k such that A249441(k) = 3.at n=34A249452
• Numbers n such that the Shevelev polynomial {m, n} has a root at m = -1.at n=30A264613
• Independence number of the n-Mycielski graph.at n=22A266550
• Decimal representation of the n-th iteration of the "Rule 185" elementary cellular automaton starting with a single ON (black) cell.at n=11A267614
• Decimal representation of the x-axis, from the origin to the right edge, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 3", based on the 5-celled von Neumann neighborhood.at n=21A277867
• Decimal representation of the x-axis, from the origin to the right edge, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 705", based on the 5-celled von Neumann neighborhood.at n=21A283651
• Decimal representation of the x-axis, from the left edge to the origin, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 813", based on the 5-celled von Neumann neighborhood.at n=21A284181