A036327 Composite numbers n such that juxtaposition of prime factors of n has length 3.

8, 12, 18, 20, 22, 26, 27, 28, 30, 33, 34, 38, 39, 42, 45, 46, 50, 51, 55, 57, 58, 62, 63, 65, 69, 70, 74, 75, 77, 82, 85, 86, 87, 91, 93, 94, 95, 98, 105, 106, 111, 115, 118, 119, 122, 123, 125, 129, 133, 134, 141, 142, 145, 146, 147, 155, 158, 159, 161, 166, 175

Offset

1,1

Comments

The last term is a(104)=679.

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..104 (full sequence)

Maple

isA036327 := proc(n) local d: d:=ifactors(n)[2]: return `if`(not isprime(n) and add(length(d[j][1])*d[j][2], j=1..nops(d))=3, n, NULL): end: seq(isA036327(n), n=2..999); # Nathaniel Johnston, Jun 22 2011

Crossrefs

Cf. A036326-A036334.

Sequence in context: A257162 A352880 A104201 * A340681 A051144 A067537

Adjacent sequences: A036324 A036325 A036326 * A036328 A036329 A036330

Keyword

nonn,base,easy,fini,full

Author

Patrick De Geest, Dec 15 1998

Status

approved