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Search: id:A133980
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| 23, 37, 211, 223, 229, 241, 271, 283, 311, 313, 317, 331, 337, 347, 353, 359, 367, 373, 379, 383, 389, 397, 523, 541, 547, 571, 719, 743, 761, 773, 797, 1117, 1123, 1129, 1153, 1171, 1319, 1361, 1367, 1373, 1723, 1741, 1747, 1753, 1759, 1783, 1789, 1931
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Not the same as A133957.
Number of terms < 10^n: 0, 2, 31, 223, 1638, 11752, 89918, ....
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MATHEMATICA
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lst = {}; semiPrimeQ[x_] := Plus @@ Last /@ FactorInteger@x == 2; f[n_] := FromDigits@ Flatten[IntegerDigits@ Table[ #[[1]], {#[[2]]}] & /@ FactorInteger@n, 2]; h[n_] := NestWhileList[ f@# &, n, ! PrimeQ@# &, 1, 6];
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CROSSREFS
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Cf. A001358, A133955, A133957.
Sequence in context: A140442 A078731 A133957 this_sequence A090312 A089782 A113893
Adjacent sequences: A133977 A133978 A133979 this_sequence A133981 A133982 A133983
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KEYWORD
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nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com) & Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 01 2007, Oct 06 2007
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