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A124982
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Nonprime numbers with a unique partition as a sum of 2 squares x^2+y^2.
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5
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0, 1, 4, 8, 9, 10, 16, 18, 20, 26, 32, 34, 36, 40, 45, 49, 52, 58, 64, 68, 72, 74, 80, 81, 82, 90, 98, 104, 106, 116, 117, 121, 122, 128, 136, 144, 146, 148, 153, 160, 162, 164, 178, 180, 194, 196, 202, 208, 212, 218, 226, 232, 234, 242, 244, 245, 256, 261, 272, 274
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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FORMULA
| A000161(n)=1. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 29 2006
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PROG
| (PARI) A000161(n)={ local(cnt=0, y2) ; for(x=0, floor(sqrt(n)), y2=n-x^2 ; if( y2>=x^2 && issquare(y2), cnt++ ; ) ; ) ; return(cnt) ; } isA124982(n)= { if( isprime(n), return(0), if(A000161(n)==1, return(1), return(0) ) ) ; } { for(n=0, 300, if( isA124982(n), print1(n, ", ") ; ) ; ) ; } - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 29 2006
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CROSSREFS
| Cf. A002145.
Sequence in context: A141608 A094906 A078542 * A073042 A094349 A118715
Adjacent sequences: A124979 A124980 A124981 * A124983 A124984 A124985
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KEYWORD
| nonn
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AUTHOR
| Artur Jasinski (grafix(AT)csl.pl), Nov 16 2006
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EXTENSIONS
| Corrected and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 29 2006
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