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A334104
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Numbers m for which A329697(m) = 4.
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9
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43, 47, 49, 57, 59, 63, 67, 69, 71, 77, 79, 81, 86, 87, 91, 93, 94, 95, 98, 99, 105, 107, 109, 111, 114, 115, 117, 118, 121, 126, 131, 134, 135, 138, 142, 143, 145, 149, 151, 154, 155, 157, 158, 159, 162, 165, 167, 169, 172, 174, 175, 179, 181, 182, 183, 185, 186, 188, 190, 195, 196, 198, 210, 214, 218, 219, 222, 225
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OFFSET
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1,1
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COMMENTS
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Squares of A334102 form a subsequence.
Among the first 12193 terms (terms < 2^31), there are terms with binary weights 2 - 16, except no terms with weight 13, 14 or 15. For example, 1025 is the first term with binary weight 2, and 65535 is the first term with binary weight 16.
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LINKS
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Antti Karttunen, Table of n, a(n) for n = 1..12193; all terms <= 2^31
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EXAMPLE
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63 = 7*9 is a term as both 7 and 9 are terms of A334102.
65535 = 3*5*17*257 is a term as it is a product of four Fermat primes, thus in four steps all odd primes can be eliminated with p -> (p-1) map.
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MATHEMATICA
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Position[Array[Length@NestWhileList[# - #/FactorInteger[#][[-1, 1]] &, #, # != 2^IntegerExponent[#, 2] &] - 1 &, 225], 4][[All, 1]] (* Michael De Vlieger, Apr 30 2020 *)
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PROG
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(PARI)
A329697(n) = if(!bitand(n, n-1), 0, 1+A329697(n-(n/vecmax(factor(n)[, 1]))));
isA334104(n) = (4==A329697(n));
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CROSSREFS
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Row 4 of A334100.
Cf. A052126, A171462, A209229, A329697, A334101, A334102, A334103, A334105, A334106.
Cf. A334094 (primes present).
Sequence in context: A045144 A187777 A105375 * A095503 A095495 A095487
Adjacent sequences: A334101 A334102 A334103 * A334105 A334106 A334107
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KEYWORD
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nonn
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AUTHOR
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Antti Karttunen, Apr 14 2020
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STATUS
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approved
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