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3, 8, 36, 240, 2520, 32340, 540540, 10210200, 232792560, 6692786100, 207030183360, 7621298624940, 311671001662020, 13387011595197240, 627972543920161440, 33204048259778536140, 1955349508631402683800, 119211141709561183622340, 7975609932439674026862360, 565799151677779228023294480, 41287621429375723111588738860
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refs;
listen;
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internal format)
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OFFSET
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0,1
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COMMENTS
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a(n) = number whose primorial base representation (A049345) begins with digits "11", followed by n zeros: 11, 110, 1100, 11000, 110000, ...
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LINKS
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FORMULA
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MATHEMATICA
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Total /@ Partition[FoldList[Times, 1, Prime@ Range[20]], 2, 1] (* Michael De Vlieger, Jun 24 2023 *)
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PROG
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(PARI) a(n) = factorback(primes(n)) + factorback(primes(n+1)); \\ Michel Marcus, Nov 23 2022
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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