A175036 -id:A175036 - cp's OEIS frontend

A175131 a(n) = 2^(n-1) mod semiprime(n).

1, 2, 4, 8, 2, 2, 1, 18, 6, 18, 1, 8, 1, 22, 4, 16, 23, 2, 14, 2, 52, 2, 49, 2, 10, 65, 64, 8, 44, 2, 64, 2, 42, 12, 62, 56, 31, 98, 81, 50, 74, 2, 1, 128, 96, 71, 60, 7, 81, 16, 94, 146, 1, 144, 108, 154, 133, 4, 46, 153, 67, 44, 88, 90, 198, 32, 14, 117

Offset: 1

Juri-Stepan Gerasimov, Dec 02 2010

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Cf. A000079, A001358, A175036, A181615.

Module[{nn=300,sems,len},sems=Select[Range[nn],PrimeOmega[#]==2&];len = Length[sems];PowerMod[2,#[[1]]-1,#[[2]]]&/@Thread[{Range[len],sems}]] (* Harvey P. Dale, May 19 2018 *)

lista(nn) = {semip = select(n->bigomega(n) == 2, vector(nn, i, i)); for (i=1, #semip, print1(2^(i-1) % semip[i], ", "););} \\ Michel Marcus, Sep 11 2013

More terms from Michel Marcus, Sep 11 2013

A177806 Triangle read by rows: T(n,k) = prime(k)^(n-1) mod prime(n), 1 <= k <= n.

Original entry on oeis.org

1, 2, 0, 4, 4, 0, 1, 6, 6, 0, 5, 4, 9, 3, 0, 6, 9, 5, 11, 7, 0, 13, 15, 2, 9, 8, 16, 0, 14, 2, 16, 7, 11, 10, 5, 0, 3, 6, 16, 12, 8, 2, 18, 9, 0, 19, 21, 4, 20, 2, 5, 17, 11, 7, 0, 1, 25, 5, 25, 5, 5, 25, 25, 1, 1, 0, 13, 28, 2, 12, 27, 15, 32, 20, 29, 23, 6, 0, 37, 40, 16, 31, 23, 4, 23, 31, 37, 25, 18, 16, 0

Offset: 1

Juri-Stepan Gerasimov, Dec 12 2010

First column is A175036.

			Triangle begins:
  1;
  2, 0;
  4, 4, 0;
  1, 6, 6, 0;
  5, 4, 9, 3, 0;

Cf. A000079, A177226.

A177806 := proc(n,k) modp((ithprime(k))^(n-1), ithprime(n)) ; end proc:
seq(seq(A177806(n,k),k=1..n),n=1..15) ;

Table[PowerMod[Prime[Range[n]], n-1, Prime[n]], {n, 15}] (* Paolo Xausa, Jun 29 2024 *)

A175156 a(n) = 2^(n-1) mod composite(n).

Original entry on oeis.org

1, 2, 4, 8, 6, 8, 8, 8, 0, 8, 4, 11, 4, 8, 9, 8, 7, 4, 4, 0, 1, 32, 9, 32, 26, 2, 24, 8, 36, 32, 26, 32, 39, 42, 4, 20, 28, 7, 32, 8, 36, 32, 4, 2, 0, 57, 64, 60, 16, 2, 40, 60, 46, 48, 71, 50, 16, 8, 72, 32, 16, 32, 64, 8, 16, 32, 24, 35, 24

Offset: 1

Juri-Stepan Gerasimov, Dec 02 2010

nonn

Cf. A000079, A002808, A175036, A175131.

lista(nn) = {compo = select(n->(! isprime(n) && (n != 1)), vector(nn, i, i)); for (i = 1, #compo, print1(2^(i-1) % compo[i], ", "););} \\ Michel Marcus, Sep 11 2013

More terms from Michel Marcus, Sep 11 2013

cp's OEIS Frontend

A175131 a(n) = 2^(n-1) mod semiprime(n).

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A177806 Triangle read by rows: T(n,k) = prime(k)^(n-1) mod prime(n), 1 <= k <= n.

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A175156 a(n) = 2^(n-1) mod composite(n).

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