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Search: id:A118698
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| A118698 |
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Smaller of two consecutive semiprimes with the same multiplicative digital root. |
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+0
1
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| 46, 65, 95, 155, 158, 185, 201, 202, 203, 205, 206, 253, 254, 278, 301, 302, 303, 305, 323, 326, 361, 382, 403, 417, 445, 451, 453, 454, 471, 473, 478, 493, 497, 501, 502, 514, 519, 526, 527, 529, 537, 538, 542, 543, 545, 554, 559, 562, 565, 566, 581, 583
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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46 and 49 are two consecutive semiprimes with the same multiplicative digital root, namely 8.
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PROGRAM
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(PARI) A031347(n)= { local(resul, ncpy); if(n<10, return(n) ); ncpy=n; resul = ncpy % 10; ncpy = (ncpy - ncpy%10)/10; while( ncpy > 0, resul *= ncpy %10; ncpy = (ncpy - ncpy%10)/10; ); return(A031347(resul)); } { oldr=0; oldn=0; for(n=5, 1000, if( bigomega(n)==2, dr=A031347(n); if(dr==oldr, print1(oldn, ", "); ); oldr=dr; oldn=n; ); ); } - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 23 2006
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CROSSREFS
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Cf. A001358.
Sequence in context: A043247 A044027 A020175 this_sequence A103381 A101577 A051413
Adjacent sequences: A118695 A118696 A118697 this_sequence A118699 A118700 A118701
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KEYWORD
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base,nonn
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AUTHOR
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Luc Stevens (lms022(AT)yahoo.com), May 20 2006
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EXTENSIONS
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Corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 23 2006
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