# [seqfan] Re: correlation A161918 and A030229

Maximilian Hasler maximilian.hasler at gmail.com
Fri Jun 26 21:26:30 CEST 2009

```A161918 should say "(counted with multiplicity)" :

(PARI)
isA161918(n)={ n+1 == sigma(n)-(n=factor(n))[,1]~*n[,2] }

? for(n=1,500, isA161918(n)&print1(n","))
6,8,10,14,15,21,22,26,33,34,35,38,39,46,51,55,57,58,62,65,69,74,77,82,85,86,87,91,
93,94,95,106,111,115,118,119,122,123,129,133,134,141,142,143,145,146,155,158,
159,161,166,177,178,183,185,187,194,201,202,203,205,206,209,213,214,215,217,218
...

isA030229(n)={ #(n=factor(n)[,2]) % 2 == 0 && (!n || vecmax(n)==1 )}

? for(n=1,500, isA030229(n)&print1(n","))
1,6,10,14,15,21,22,26,33,34,35,38,39,46,51,55,57,58,62,65,69,74,77,82,85,86,87,91,
93,94,95,106,111,115,118,119,122,123,129,133,134,141,142,143,145,146,155,158,
159,161,166,177,178,183,185,187,194,201,202,203,205,206,209,210,213,214,215,217,
...

? for(n=1,2000, isA030229(n) != isA161918(n) &&print1(n","))
1,8,210,330,390,462,510,546,570,690,714,770,798,858,870,910,930,966,1110,
1122,1155,1190,1218,1230,1254,1290,1302,1326,1330,1365,1410,1430,1482,
1518,1554,1590,1610,1722,1770,1785,1794,1806,1830,1870,1914,1938,1974,1995,

> Are these two sequences related?

well, everything is *somehow* "related" ...

Maximilian

```