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A278252
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Least number with the prime signature of the n-th tetrahedral number, binomial(n+2,3).
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2
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1, 4, 6, 12, 6, 24, 60, 120, 30, 60, 30, 60, 30, 240, 120, 240, 30, 420, 210, 420, 30, 120, 180, 360, 180, 1260, 420, 420, 30, 480, 240, 480, 210, 4620, 2310, 420, 30, 840, 420, 840, 30, 420, 2310, 4620, 210, 240, 360, 3600, 180, 1260, 210, 1260, 420, 27720, 4620, 840, 30, 420, 210, 420, 210, 6720, 36960, 6720, 210, 420, 210, 4620, 210, 9240, 420, 840, 60, 1260
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OFFSET
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1,2
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LINKS
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FORMULA
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MATHEMATICA
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Table[Times @@ MapIndexed[(Prime@ First@ #2)^#1 &, #] &@ If[Length@ # == 1 && #[[1, 1]] == 1, {0}, Reverse@ Sort@ #[[All, -1]]] &@ FactorInteger[ Binomial[n + 2, 3]], {n, 74}] (* Michael De Vlieger, Nov 21 2016 *)
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PROG
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(Scheme)
(define (A000292 n) (/ (* n (+ 1 n) (+ 2 n)) 6))
(PARI) a(n)=my(e=vecsort(factor(binomial(n+2, 3))[, 2], , 4)~); factorback(primes(#e), e) \\ Charles R Greathouse IV, Feb 22 2017
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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