OFFSET
1,1
COMMENTS
Terms through row n, sorted, will provide terms forA077553through row n*(n+1)/2.
LINKS
Reinhard Zumkeller,Rows n = 1..125 of triangle, flattened
FORMULA
The n-th row consists of n terms, prime(n)*prime(i), i=1..n.
EXAMPLE
Triangle begins:
4;
6, 9;
10, 15, 25;
14, 21, 35, 49;
22, 33, 55, 77, 121;
26, 39, 65, 91, 143, 169;
MAPLE
T:= (n, k) -> ithprime(n) * ithprime(k):
seq(print(seq(T(n, k), k = 1..n)), n = 1..11); #Peter Luschny,Jun 25 2024
MATHEMATICA
Table[ Prime[j]*Prime[k], {j, 11}, {k, j}] // Flatten (*Robert G. Wilson v,Feb 06 2017 *)
PROG
(Haskell)
a087112 n k = a087112_tabl!! (n-1)!! (k-1)
a087112_row n = map (* last ps) ps where ps = take n a000040_list
a087112_tabl = map a087112_row [1..]
--Reinhard Zumkeller,Nov 25 2012
(PARI)A087112(n) = { n--; my(c = (sqrtint(8*n + 1) - 1) \ 2); (prime(1+c) * prime(1+(n-binomial(1+c, 2)))); }; \\Antti Karttunen,Feb 29 2024
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Ray Chandler,Aug 21 2003
STATUS
approved