A101174
Triangle formed by grouping the natural numbers so that the n-th row contains n numbers whose product has exactly n prime divisors, minimizing (1) final term of row and (2) product of terms of row.
Original entry on oeis.org
2, 3, 4, 1, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 45, 48, 44, 46, 47, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72
Offset: 1
Triangle begins:
2
3,4
1,5,6
7,8,9,10
11,12,13,14,16
15,17,18,19,20,21
22,23,24,25,26,27,28
29,30,31,32,33,34,35,36
37,38,39,40,41,42,43,45,48
44,46,47,49,50,51,52,53,54,55
56,57,58,59,60,61,62,63,64,65,66
67,68,69,70,71,72,73,74,75,76,77,80
78,79,81,82,83,84,85,86,87,88,89,90,91
A093850
Triangle T(n,k) = 10^(n-1) -1 + k*floor(9*10^(n-1)/(n+1)), with 1 <= r <= n, read by rows.
Original entry on oeis.org
4, 39, 69, 324, 549, 774, 2799, 4599, 6399, 8199, 24999, 39999, 54999, 69999, 84999, 228570, 357141, 485712, 614283, 742854, 871425, 2124999, 3249999, 4374999, 5499999, 6624999, 7749999, 8874999, 19999999, 29999999, 39999999, 49999999, 59999999, 69999999, 79999999, 89999999
Offset: 1
Triangle begins with:
4;
39, 69;
324, 549, 774;
2799, 4599, 6399, 8199;
24999, 39999, 54999, 69999, 84999;
....
-
[[10^(n-1) -1 +k*Floor(9*10^(n-1)/(n+1)): k in [1..n]]: n in [1..8]]; // G. C. Greubel, Mar 21 2019
-
A093850 := proc(n,r)
10^(n-1)-1+r*floor(9*10^(n-1)/(n+1)) ;
end proc:
seq(seq(A093850(n,r),r=1..n),n=1..14) ; # R. J. Mathar, Sep 28 2011
-
Table[# -1 +r*Floor[9*#/(n+1)] &[10^(n-1)], {n, 8}, {r, n}]//Flatten (* Michael De Vlieger, Jul 18 2016 *)
-
{T(n,k) = 10^(n-1) -1 +k*floor(9*10^(n-1)/(n+1))}; \\ G. C. Greubel, Mar 21 2019
-
[[10^(n-1) -1 +k*floor(9*10^(n-1)/(n+1)) for k in (1..n)] for n in (1..8)] # G. C. Greubel, Mar 21 2019
Showing 1-2 of 2 results.
Comments