OFFSET
1,1
COMMENTS
a(181) = 27 is the first term greater than 19. This is because prime(181)/181 > 6 for the first time. In general this sequence is determined by prime(n)/n: the pattern for each row of the triangle is that it ends with prime(n), preceded by multiples of k = prime(n)/n down to k^2, then the largest multiple of k-1 less than k^2 and the largest multiple of k-2 less than that and so on. This sequence gives the multiple of 1. See A000960 for the sequence that gives the ending value for each starting k.
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
MATHEMATICA
t[1, n_]:= Prime[n];
t[m_, n_]/; 1<m<=n:= t[m, n]= (n-m+1)*Floor[(t[m-1, n]-1)/(n-m+1)];
t[_, _]=0;
Table[A119447[n], {n, 100}] (* G. C. Greubel, Apr 07 2023 *)
PROG
(Magma)
function t(n, k) // t = A119446
if k eq 1 then return NthPrime(n);
else return (n-k+1)*Floor((t(n, k-1) -1)/(n-k+1));
end if;
end function;
[t(n, n): n in [1..100]]; // G. C. Greubel, Apr 07 2023
(SageMath)
def t(n, k): # t = A119446
if (k==1): return nth_prime(n)
else: return (n-k+1)*((t(n, k-1) -1)//(n-k+1))
def A119447(n): return t(n, n)
[A119447(n) for n in range(1, 101)] # G. C. Greubel, Apr 07 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Joshua Zucker, May 20 2006
STATUS
approved