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A182944 Square array A(i,j), i >= 1, j >= 1, of prime powers prime(i)^j, by descending antidiagonals. 12
2, 4, 3, 8, 9, 5, 16, 27, 25, 7, 32, 81, 125, 49, 11, 64, 243, 625, 343, 121, 13, 128, 729, 3125, 2401, 1331, 169, 17, 256, 2187, 15625, 16807, 14641, 2197, 289, 19, 512, 6561, 78125, 117649, 161051, 28561, 4913, 361, 23 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
We alternatively refer to this sequence as a triangle T(.,.), with T(n,k) = A(k,n-k+1) = prime(k)^(n-k+1).
The monotonic ordering of this sequence, prefixed by 1, is A000961.
The joint-rank array of this sequence is A182869.
Main diagonal gives A062457. - Omar E. Pol, Sep 11 2018
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..11325 (rows 1..150, flattened)
Michael De Vlieger, Diagram showing row n of triangle in a semicircle as noted, with a color function associated with the magnitude of T(n,k) compared to 2^n in light blue, where prime(n) is the smallest and the prime power indicated in red the largest in the row.
FORMULA
From Peter Munn, Dec 29 2019: (Start)
A(i,j) = A182945(j,i) = A319075(j,i).
A(i,j) = A242378(i-1,2^j) = A329332(2^(i-1),j).
A(i,i) = A062457(i).
(End)
EXAMPLE
Square array A(i,j) begins:
i \ j: 1 2 3 4 5 ...
---\-------------------------------------
1: 2, 4, 8, 16, 32, ...
2: 3, 9, 27, 81, 243, ...
3: 5, 25, 125, 625, 3125, ...
4: 7, 49, 343, 2401, 16807, ...
...
The triangle T(n,k) begins:
n\k: 1 2 3 4 5 6 ...
1: 2
2: 4 3
3: 8 9 5
4: 16 27 25 7
5: 32 81 125 49 11
6: 64 243 625 343 121 13
...
MATHEMATICA
TableForm[Table[Prime[n]^j, {n, 1, 14}, {j, 1, 8}]]
CROSSREFS
Cf. A000961, A006939 (row products of triangle), A062457, A182945, A332979 (row maxima of triangle).
Columns: A000040 (1), A001248 (2), A030078 (3), A030514 (4), A050997 (5), A030516 (6), A092759 (7), A179645 (8), A179665 (9), A030629 (10).
A319075 extends the array with 0th powers.
Subtable of A242378, A284457, A329332.
Sequence in context: A269851 A284457 A365656 * A269385 A252755 A366275
KEYWORD
nonn,tabl
AUTHOR
Clark Kimberling, Dec 14 2010
EXTENSIONS
Clarified in respect of alternate reading as a triangle by Peter Munn, Aug 28 2022
STATUS
approved

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Last modified April 18 18:58 EDT 2024. Contains 371781 sequences. (Running on oeis4.)