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Search: id:A117720
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| A117720 |
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Numbers for which the sum of the digits is the square root of the product of their digits. |
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+0
2
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| 0, 1, 999, 2558, 2585, 2855, 3366, 3636, 3663, 4444, 5258, 5285, 5528, 5582, 5825, 5852, 6336, 6363, 6633, 8255, 8525, 8552, 12489, 12498, 12849, 12894, 12948, 12984, 13377, 13737, 13773, 14289, 14298, 14829, 14892, 14928, 14982, 17337, 17373
(list; graph; listen)
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OFFSET
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0,3
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EXAMPLE
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2558 is in the sequence because (1)the sum of its digits is 2+5+5+8=20,(2)the product of its digits is 2*5*5*8=400 and 20 is the square root of 400.
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PROGRAM
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(PARI) sudig(i, suOrmul)= { local(nshft, resul) ; nshft = i ; resul = nshft % 10 ; nshft = nshft \ 10 ; while(nshft>0, if(suOrmul==0, resul += nshft % 10, resul *= nshft % 10 ) ; nshft \= 10 ; ) ; return(resul) ; } { for(n=0, 15000, summ = sudig(n, 0) ; mull = sudig(n, 1) ; if( summ^2==mull, print1(n, ", ") ) ; ) ; } - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 21 2006
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CROSSREFS
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Sequence in context: A091362 A091365 A043527 this_sequence A110401 A164813 A164814
Adjacent sequences: A117717 A117718 A117719 this_sequence A117721 A117722 A117723
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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), Apr 13 2006
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 21 2006
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