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Search: id:A100658
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| A100658 |
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Composite numbers with at least 2 factors that have different digital roots. |
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+0
2
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| 6, 10, 12, 14, 15, 18, 20, 21, 24, 26, 28, 30, 33, 34, 35, 36, 38, 39, 40, 42, 45, 46, 48, 50, 51, 52, 54, 55, 56, 57, 60, 62, 63, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 82, 84, 85, 86, 87, 90, 91, 92, 93, 95, 96, 98, 99, 100, 102, 104, 105, 106, 108, 110, 111, 112
(list; graph; listen)
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OFFSET
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1,1
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PROGRAM
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(PARI) nsamedr(n) = { local(j); for(j=2, n, if(!isprime(j)&!issamedr(j), print1(j", ")) ) } issamedr(n) = { local(f, a, ln, x); f=0; a=ifactor(n); ln=length(a); for(x=1, ln-1, if(droot(a[x])<>droot(a[x+1]), f=1; break)); if(f==0&ln>1, return(1), return(0)) } droot(n) = \ the digital root of a number. { local(x); x= n%9; if(x>0, return(x), return(9)) }
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CROSSREFS
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Adjacent sequences: A100655 A100656 A100657 this_sequence A100659 A100660 A100661
Sequence in context: A030231 A056760 A084227 this_sequence A069059 A139587 A119313
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KEYWORD
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base,easy,nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), Jan 02 2005
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