A277129 Largest m < n such that 2^m == 2^n (mod n).
0, 1, 1, 3, 1, 4, 4, 7, 3, 6, 1, 10, 1, 11, 11, 15, 9, 12, 1, 16, 15, 12, 12, 22, 5, 14, 9, 25, 1, 26, 26, 31, 23, 26, 23, 30, 1, 20, 27, 36, 21, 36, 29, 34, 33, 35, 24, 46, 28, 30, 43, 40, 1, 36, 35, 53, 39, 30, 1, 56, 1, 57, 57, 63, 53, 56, 1, 60, 47, 58, 36, 66, 64, 38, 55, 58, 47, 66, 40, 76, 27, 62, 1
Offset: 1
Keywords
Programs
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Mathematica
Table[m = n - 1; While[Mod[2^m, n] != Mod[2^n, n], m--]; m, {n, 83}] (* Michael De Vlieger, Oct 02 2016 *) -
PARI
a(n) = {if(n==0,return(0));my(pt = valuation(n, 2), odd = n/2^pt, ul = odd-A002326(odd\2)); forstep(i = n-1, ul, -1, if(Mod(2,n)^i==Mod(2,n)^n,return(i)))} \\ David A. Corneth, Oct 01 2016 A002326(n)=if(n<0, 0, znorder(Mod(2, 2*n+1)))
Extensions
More terms from Altug Alkan, Oct 01 2016
Comments