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 A209049 Smallest pentagonal number with n prime factors (counted with multiplicity). 1
 1, 5, 22, 12, 210, 176, 1520, 1080, 8400, 55200, 273280, 43776, 2624832, 7173360, 71660160, 100659200, 34255872, 178962432, 3623854080, 17895751680, 5413478400, 43690752000, 927712542720, 733008101376, 1789570252800, 35917382287360, 50649120571392 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Pentagonal analogy of A075088. LINKS MATHEMATICA k = 1; t = Table[0, {50}]; While[k < 500000001, a = PrimeOmega[k] + PrimeOmega[3 k - 1] - 1; If[ t[[a + 1]] == 0, t[[a + 1]] = k; Print[{k, a}]]; k++]; # (3 # - 1)/2 & /@ t CROSSREFS Cf. A075088, A209048. Sequence in context: A247937 A343840 A270406 * A217444 A063619 A229801 Adjacent sequences:  A209046 A209047 A209048 * A209050 A209051 A209052 KEYWORD nonn AUTHOR Robert G. Wilson v, Mar 04 2012 STATUS approved

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Last modified September 28 09:32 EDT 2021. Contains 347714 sequences. (Running on oeis4.)