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A067598
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Decimal encoding of the prime factorization of n is a multiple of n.
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2
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21, 36, 8277, 22987, 31199, 59577, 2092101, 25224589, 29963201, 564423629, 1353149983
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| If n = p_1^e_1 * ... * p_r^e_r with p_1 < ... < p_r, then the decimal encoding is p_1 e_1...p_r e_r. For example, 15 = 3^1 * 5^1, so has decimal encoding 3151.
a(12) > 10^10. [From Donovan Johnson (donovan.johnson(AT)yahoo.com), Mar 26 2010]
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EXAMPLE
| The prime factorization of 21 = 3^1 * 7^1 with corresponding encoding 3171. 3171 = 21 * 151, a multiple of 21. So 21 is a term of the sequence.
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MATHEMATICA
| Select[Range[100000], Mod[FromDigits[Flatten[IntegerDigits /@ Flatten[FactorInteger[ # ]]]], # ] ==0 &]
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PROG
| (PARI) {a067598(a, b) = local(n, v); for(n=max(2, a), b, v=factor(n); if(eval(concat(vector(matsize(v)[1], k, concat(vector(matsize(v)[2], j, Str(v[k, j]))))))%n==0, print1(n, ", ")))}
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CROSSREFS
| Sequence in context: A001491 A112352 A168513 * A043683 A173589 A043572
Adjacent sequences: A067595 A067596 A067597 * A067599 A067600 A067601
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KEYWORD
| base,easy,nonn
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AUTHOR
| Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Jan 31 2002
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EXTENSIONS
| Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 02 2002
Two more terms from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Feb 20 2002
a(10)-a(11) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Mar 26 2010
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