A177266 Triangle read by rows: R(n,k) = 2^(semiprime(n)-semiprime(k)) mod semiprime(n).
1, 4, 1, 5, 8, 1, 4, 6, 2, 1, 2, 4, 4, 2, 1, 8, 2, 4, 2, 2, 1, 11, 8, 1, 11, 2, 1, 1, 14, 20, 8, 4, 14, 18, 2, 1, 2, 13, 11, 18, 23, 24, 16, 8, 1, 10, 22, 6, 16, 14, 20, 6, 16, 2, 1, 17, 29, 16, 8, 17, 25, 4, 2, 25, 29, 1, 30, 16, 2, 18, 16, 8, 32, 16, 2, 18, 2, 1, 23, 32, 4, 2, 22
Offset: 1
Examples
Triangle begins: 1, 4, 1, 5, 8, 1, 4, 6, 2, 1, 2, 4, 4, 2, 1, 8, 2, 4, 2, 2, 1,
Programs
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Mathematica
Table[PowerMod[2, #[[n]] - #[[;;n]], #[[n]]], {n, Length[#]}] & [Select[Range[50], PrimeOmega[#] == 2 &]] (* Paolo Xausa, Jun 28 2024 *) -
PARI
trg(nn) = {semip = select(n->bigomega(n) == 2, vector(nn, i, i)); for (n = 1, #semip, for (k = 1, n, print1(2^(semip[n] - semip[k]) % semip[n], ", ");); print(););} \\ Michel Marcus, Sep 11 2013
Extensions
Corrected by D. S. McNeil, Dec 10 2010