|
%I #17 Feb 22 2017 13:59:23
%S 1,4,6,12,6,24,60,120,30,60,30,60,30,240,120,240,30,420,210,420,30,
%T 120,180,360,180,1260,420,420,30,480,240,480,210,4620,2310,420,30,840,
%U 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
%N Least number with the prime signature of the n-th tetrahedral number, binomial(n+2,3).
%H Antti Karttunen, <a href="/A278252/b278252.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A046523(A000292(n)) = A046523(binomial(n+2,3)).
%t 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 *)
%o (Scheme)
%o (define (A278252 n) (A046523 (A000292 n)))
%o (define (A000292 n) (/ (* n (+ 1 n) (+ 2 n)) 6))
%o (PARI) a(n)=my(e=vecsort(factor(binomial(n+2,3))[,2],,4)~); factorback(primes(#e),e) \\ _Charles R Greathouse IV_, Feb 22 2017
%Y Diagonal 3 of A278218.
%Y Cf. A000292, A046523.
%K nonn
%O 1,2
%A _Antti Karttunen_, Nov 19 2016
|
