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Search: id:A091022
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| A091022 |
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Semiprimes with semiprime indices. |
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+0
7
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| 10, 15, 25, 26, 38, 39, 58, 62, 74, 77, 94, 95, 106, 118, 119, 141, 145, 155, 166, 177, 178, 194, 203, 213, 219, 235, 254, 265, 267, 274, 291, 298, 299, 301, 329, 346, 362, 377, 381, 386, 391, 393, 411, 422, 427, 454, 458, 466, 471, 473, 502, 514, 515, 519
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Semiprime of semiprime of n: a(n) = A001358(A001358(n)). - Jonathan Vos Post (jvospost2(AT)yahoo.com), Apr 29 2005
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EXAMPLE
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10 is a member because 10 is 4th semiprime and 4 is a semiprime.
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PROGRAM
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(PARI) A001358()= { local(resul); resul = [4]; for(n=5, 1000, if ( bigomega(n) == 2, resul =concat(resul, n); ); ); return(resul); } { spr=Vec(A001358()); sprlen=(matsize(spr))[2]; for(n=1, sprlen, if( spr[n]>=sprlen, break; ); print1(spr[spr[n]], ", "); ); } - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 23 2006
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CROSSREFS
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Cf. A001358, A007097.
Sequence in context: A034961 A117847 A057990 this_sequence A133372 A100916 A001750
Adjacent sequences: A091019 A091020 A091021 this_sequence A091023 A091024 A091025
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Feb 24 2004
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