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Search: id:A067598
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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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+0
2
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| 21, 36, 8277, 22987, 31199, 59577, 2092101, 25224589, 29963201
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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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.
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EXAMPLE
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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
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Select[Range[100000], Mod[FromDigits[Flatten[IntegerDigits /@ Flatten[FactorInteger[ # ]]]], # ] ==0 &]
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PROGRAM
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(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
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Adjacent sequences: A067595 A067596 A067597 this_sequence A067599 A067600 A067601
Sequence in context: A155710 A001491 A112352 this_sequence A043683 A043572 A043728
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KEYWORD
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base,easy,nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Jan 31 2002
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EXTENSIONS
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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
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