login
A365448
Array read by antidiagonals: row 1 is the semiprimes A001358; for m > 1, row m is the semiprimes that are the sum of two successive terms of row m-1.
0
4, 6, 10, 9, 15, 25, 10, 51, 146, 422, 14, 69, 201, 551, 973, 15, 77, 221, 667, 1858, 2831, 21, 85, 249, 1191, 89855, 312493, 127418369, 22, 95, 302, 1343, 110099, 2676567, 154171217
OFFSET
1,1
EXAMPLE
The first 7 rows are
4, 6, 9, 10, 14, 15, 21, 22, 25, 26, ...
10, 15, 51, 69, 77, 85, 95, 106, 115, 134, ...
25, 146, 201, 221, 249, 302, 365, 529, 662, 681, ...
422, 551, 667, 1191, 1343, 2661, 6621, 11207, 13637, 14183, ...
973, 1858, 89855, 110099, 202394, 332377, 352147, 383507, 469231, 528923, ...
2831, 312493, 2676567, 3754285, 4027807, 9438362, 10568289, 20372991, 20590454, 21591014, ...
127418369, 154171217, 213938227, 242408953, 296917233, 325907227, 345235903, 367725381, ...
T(4,3) = 667 is a term because 667 = 23 * 29 is a semiprime and 667 = 392 + 365 where 302 = T(3,6) and 365 = T(3,7).
MAPLE
R[1]:= select(t -> numtheory:-bigomega(t) = 2, [$1..5*10^6]): M[1]:= nops(R[1]):
for i from 2 do
R[i]:= select(t -> numtheory:-bigomega(t) = 2, R[i-1][1..M[i-1]-1] + R[i-1][2..M[i-1]]);
M[i]:= nops(R[i]);
if M[i] = 0 then break fi
od:
L:= NULL:
for k from 2 to 8 do
L:= L, seq(R[i][k-i], i=1..k-1)
od:
L;
CROSSREFS
Cf. A001358 (first row), A092192 (second row), A366167 (third row).
Sequence in context: A292767 A117622 A188673 * A193951 A129854 A088682
KEYWORD
nonn,tabl,more
AUTHOR
Zak Seidov and Robert Israel, Oct 03 2023
STATUS
approved