login
A370134
Triangle read by rows: T(n,k) = A002110(n) + A002110(k), 1 <= k <= n; sums of two primorials > 1, not necessarily distinct.
4
4, 8, 12, 32, 36, 60, 212, 216, 240, 420, 2312, 2316, 2340, 2520, 4620, 30032, 30036, 30060, 30240, 32340, 60060, 510512, 510516, 510540, 510720, 512820, 540540, 1021020, 9699692, 9699696, 9699720, 9699900, 9702000, 9729720, 10210200, 19399380, 223092872, 223092876, 223092900, 223093080, 223095180, 223122900, 223603380
OFFSET
1,1
FORMULA
For n >= 1, A276150(a(n)) = 2.
EXAMPLE
Triangle begins as:
4;
8, 12;
32, 36, 60;
212, 216, 240, 420;
2312, 2316, 2340, 2520, 4620;
30032, 30036, 30060, 30240, 32340, 60060;
510512, 510516, 510540, 510720, 512820, 540540, 1021020;
9699692, 9699696, 9699720, 9699900, 9702000, 9729720, 10210200, 19399380;
MATHEMATICA
nn = 20; MapIndexed[Set[P[First[#2] - 1], #1] &, FoldList[Times, 1, Prime@ Range[nn + 1]]]; Table[(P[n] + P[k]), {n, nn}, {k, n}] (* Michael De Vlieger, Mar 08 2024 *)
PROG
(PARI)
A002110(n) = prod(i=1, n, prime(i));
A370134(n) = { n--; my(c = (sqrtint(8*n + 1) - 1) \ 2); (A002110(1+c) + A002110(1+n - binomial(c + 1, 2))); };
CROSSREFS
A370121 without its leftmost column. Subsequence of A370132.
Cf. A088860 (right edge).
Sequence in context: A302829 A055079 A081833 * A035403 A050908 A232901
KEYWORD
nonn,tabl
AUTHOR
Antti Karttunen, Mar 07 2024
STATUS
approved