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A289053 Array T(i,k) read by antidiagonals: position of prime(i)*prime(k) in A001358. 0
1, 3, 2, 9, 6, 4, 17, 13, 7, 5, 40, 26, 19, 11, 8, 56, 48, 31, 23, 15, 10, 90, 75, 61, 39, 28, 18, 12, 114, 103, 79, 68, 44, 34, 20, 14, 164, 135, 122, 94, 81, 54, 37, 24, 16, 253, 199, 172, 152, 118, 101, 65, 49, 30, 21 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..55.

EXAMPLE

Array begins:

    1      2      4      5      8     10    12    14    16    21

    3      6      7     11     15     18    20    24    30

    9     13     19     23     28     34    37    49

   17     26     31     39     44     54    65

   40     48     61     68     81    101

   56     75     79     94    118

   90    103    122    152

  114    135    172

  164    199

  253

MATHEMATICA

With[{nn = 11}, Function[s, Table[Position[s, Prime[i] Prime[k]][[1, 1]], {i, nn}, {k, i, 1, -1}] // Flatten]@ Select[Range[Prime[nn]^2], PrimeOmega@ # == 2 &]] (* Michael De Vlieger, Jun 23 2017 *)

CROSSREFS

Cf. A000040, A001358, A115392 (1st row), A128301 (1st column).

Sequence in context: A140590 A329211 A164279 * A191539 A235539 A191449

Adjacent sequences:  A289050 A289051 A289052 * A289054 A289055 A289056

KEYWORD

nonn,tabl

AUTHOR

Zak Seidov, Jun 23 2017

STATUS

approved

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Last modified November 29 18:31 EST 2021. Contains 349416 sequences. (Running on oeis4.)