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Search: id:A133126
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| A133126 |
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Semiprimes which are equal to product of two successive primes and also to sum of three successive primes. |
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1
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| 15, 143, 11021, 154433, 159197, 194477, 213443, 364807, 412163, 462391, 484391, 685583, 853751, 1032247, 1299479, 1633283, 2039183, 2108303, 2301253, 2985959, 3474487, 3802499, 3904567, 3960091, 4028033, 4536899, 5048993, 5517797
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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15=3*5=3+5+7,
143=11*13=43+47+53,
11021=103*107=3671+3673+3677,
154433=389*397=51473+51479+51481,
159197=397*401=53051+53069+53077,
194477=439*443=64811+64817+64849,
213443=461*463=71143+71147+71153.
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MATHEMATICA
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b = {}; For[n = 2, n < 1000, n++, a = Prime[n]*Prime[n + 1]; If[a == Prime[PrimePi[a/3]] + Prime[PrimePi[a/3] + 1] + Prime[PrimePi[a/3] + 2] || a == Prime[PrimePi[a/3] - 1] + Prime[PrimePi[a/3]] + Prime[PrimePi[a/3] + 1], AppendTo[b, a]]]; b - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Sep 24 2007
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CROSSREFS
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Sequence in context: A093117 A045724 A071700 this_sequence A092398 A026893 A025440
Adjacent sequences: A133123 A133124 A133125 this_sequence A133127 A133128 A133129
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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), Sep 19 2007
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com) and R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 24 2007
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