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URL: https://oeis.org/A052053

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A052053
Digits of the prime factors of composite a(n) are not shared.
2
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
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
KEYWORD
nonn,easy,base
AUTHOR
Patrick De Geest, Dec 15 1999
STATUS
approved