A090323 - OEIS

%I #2 Mar 31 2012 13:21:56

%S 1,2,11,3,21,4,31,111,5,22,41,211,6,32,51,311,7,42,221,61,1111,33,411,

%T 8,52,321,71,2111,43,511,9,62,421,81,3111,53,222,611,10,331,72,2211,

%U 44,521,91,4111,63,322,711,11,431,82,11111

%N Literal string created by the first time an orderless exponent appears; the exponents from A025487.

%C There is a pattern to this, compare the values between 7 and 8 and 8 and 9 for example.

%e The sequence corresponds to 2(1), 4(2), 6(11), 8(3), 12(21), 16(4). 18 is counted as (21) and so does not appear.

%o (PARI) { v=[2,4,6,8,12,16,24,30,32,36,48,60,64,72,96,120,128,144,180, 192,210,216,240,256,288,360,384,420,432,480,512,576,720,768, 840,864,900,960,1024,1080,1152,1260,1296,1440,1536,1680, 1728,1800,1920,2048,2160,2304,2310]; for (i=1,length(v),print1(","); for (j=1,length(factor(v[i])[,2]), print1(factor(v[i])[j,2]))) }

%Y Cf. A025487.

%K nonn

%O 1,2

%A _Jon Perry_, Jan 26 2004