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Search: id:A073172
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| A073172 |
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The value of index for composite numbers with square subscripts which are also square numbers. |
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+0
2
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| 1, 4, 9, 1024, 5621641, 10188864, 27657081, 308950929
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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Solutions to c[x^2]=y^2, values of x^2; where c(j)=jth composite number; See program.
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EXAMPLE
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a(4)=1024 corresponds to composite=1225=35.35=c(1024)=c(32.32).
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MATHEMATICA
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c[x_] := FixedPoint[x+PrimePi[ # ]+1&, x] Do[s=c[n^2]; If[IntegerQ[Sqrt[s]], Print[n^2]], {n, 1, 1000000}]
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CROSSREFS
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Cf. A002808, A073171.
Sequence in context: A063248 A027522 A028869 this_sequence A111443 A051499 A008345
Adjacent sequences: A073169 A073170 A073171 this_sequence A073173 A073174 A073175
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jul 19 2002
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