A379560 - OEIS

A379560

a(1) = 1, a(2) = 4; for n > 2, a(n) is the smallest unused positive nonsquarefree number that shares a factor with a(n-1).

%I #8 Dec 26 2024 10:14:49

%S 1,4,8,12,9,18,16,20,24,27,36,28,32,40,25,45,48,44,50,52,54,56,49,63,

%T 60,64,68,72,75,80,76,84,81,90,88,92,96,98,100,104,108,99,117,120,112,

%U 116,124,126,128,132,121,176,136,140,125,135,144,147,150,148,152,156,153,162,160,164,168,171,180,172,184,188,192,189,175,196,198,200,204,207,216

%N a(1) = 1, a(2) = 4; for n > 2, a(n) is the smallest unused positive nonsquarefree number that shares a factor with a(n-1).

%H Scott R. Shannon, <a href="/A379560/b379560.txt">Table of n, a(n) for n = 1..10000</a>

%e a(3) = 8 as a(2) = 4 and 8 is the smallest unused nonsquarefree number (8 = 2^3) that shares a factor with 4.

%Y Cf. A013929, A100113, A064413, A379248.

%K nonn

%O 1,2

%A _Scott R. Shannon_, Dec 26 2024