A052053 Digits of the prime factors of composite a(n) are not shared.

6, 10, 14, 15, 21, 22, 26, 30, 33, 34, 35, 38, 42, 51, 55, 57, 62, 65, 66, 70, 74, 77, 82, 85, 86, 87, 91, 94, 95, 102, 105, 106, 110, 114, 115, 118, 122, 123, 130, 133, 134, 141, 142, 145, 146, 154, 155, 158, 161, 165, 166, 170, 177, 178, 182, 183, 185, 190, 194

Offset

1,1

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Example

141 = 3 * 47 is OK because the sets (3) and (4,7) share no digits. 39 = 3 * 13 is rejected because the sets (3) and (1,3) share the digit 3.

Maple

with(numtheory): isA052053 := proc(n) local d, dd, m, j, k: if(isprime(n) or not issqrfree(n))then return false: fi: d:=factorset(n): m:=nops(d): for k from 1 to m do dd[k]:=convert(convert(d[k], base, 10), set): od: for j from 1 to m do for k from j+1 to m do if(not dd[j] intersect dd[k] = {})then return false: fi: od: od: return true: end: seq(`if`(isA052053(n), n, NULL), n=2..200); # Nathaniel Johnston, Jun 02 2011

Crossrefs

Cf. A052054.

Sequence in context: A000469 A120944 A327829 * A276818 A325259 A320911

Adjacent sequences: A052050 A052051 A052052 * A052054 A052055 A052056

Keyword

nonn,easy,base

Author

Patrick De Geest, Dec 15 1999

Status

approved