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A369979
Three-dimensional array giving all products of three (not necessarily distinct) odd primes.
6
27, 45, 75, 125, 63, 105, 175, 147, 245, 343, 99, 165, 275, 231, 385, 539, 363, 605, 847, 1331, 117, 195, 325, 273, 455, 637, 429, 715, 1001, 1573, 507, 845, 1183, 1859, 2197, 153, 255, 425, 357, 595, 833, 561, 935, 1309, 2057, 663, 1105, 1547, 2431, 2873, 867, 1445, 2023, 3179, 3757, 4913, 171, 285, 475, 399, 665, 931
OFFSET
1,1
COMMENTS
For n > 20, a(n) < A370138(n).
LINKS
FORMULA
For n > 1, a(n) = A276086(A370137(n)).
EXAMPLE
Table T(x,y,z) = A065091(x) * A065091(y) * A065091(z), x >= y >= z >= 1, is read by lexicographical ordering of weakly decreasing triplets (x,y,z):
(1, 1, 1) -> 3*3*3 = 27;
(2, 1, 1) -> 5*3*3 = 45, (2, 2, 1) -> 5*5*3 = 75, (2, 2, 2) -> 5*5*5 = 125;
(3, 1, 1) -> 7*3*3 = 63, (3, 2, 1) -> 7*5*3 = 105, (3, 2, 2) -> 7*5*5 = 175, (3, 3, 1) -> 7*7*3 = 147, (3, 3, 2) -> 7*7*5 = 245, (3, 3, 3) -> 7*7*7 = 343.
MATHEMATICA
Table[Prime[i]*Prime[j]*Prime[k], {i, 2, 8}, {j, 2, i}, {k, 2, j}] // Flatten (* Michael De Vlieger, Mar 09 2024 *)
PROG
(PARI)
up_to = 15180;
A369979list(up_to) = { my(v = vector(up_to), i=0); for(x=1, oo, for(y=1, x, for(z=1, y, i++; if(i > up_to, return(v)); v[i] = prime(1+x)*prime(1+y)*prime(1+z)))); (v); };
v369979 = A369979list(up_to);
A369979(n) = v369979[n];
CROSSREFS
Cf. A000292, A046316 (same sequence sorted into ascending order), A065091, A276086, A370137, A370138.
Cf. also A087112.
Sequence in context: A228057 A113481 A328897 * A039325 A043148 A043928
KEYWORD
nonn,tabf
AUTHOR
Antti Karttunen, Mar 09 2024
STATUS
approved