Search: id:A056157 Results 1-1 of 1 results found. %I A056157 %S A056157 53,173,277,317,397,769,773,797,809,853,1009,1013,1093,1493,1613,1637, %T A056157 1693,1721,2129,2213,2333,2477,2521,2557,2729,2797,2837,3329,3373,3517, %U A056157 3637,3733,3797,3853,3877,4133,4241,4253,4373,4493,4729,4733,4877,5081 %N A056157 Primes p for which the period of reciprocal = (p-1)/4. %C A056157 Cyclic numbers of the fourth degree (or fourth order): the reciprocals of these numbers belong to one of four different cycles. Each cycle has the (number minus 1)/4 digits. %H A056157 T. D. Noe, Table of n, a(n) for n=1..1000 %H A056157 Index entries for sequences related to decimal expansion of 1/n %t A056157 f[n_Integer] := Block[{ds = Divisors[n - 1]}, (n - 1)/Take[ ds, Position[ PowerMod[ 10, ds, n], 1] [[1, 1]]] [[ -1]]]; Select[ Prime[ Range[4, 700]], f[ # ] == 4 &] - Robert G. Wilson v (rgwv(AT)rgwv.com) %t A056157 LP[ n_Integer ] := (ds = Divisors[ n - 1 ]; Take[ ds, Position[ PowerMod[ 10, ds, n ], 1 ][ [ 1, 1 ] ] ][ [ -1 ] ]); CL[ n_Integer ] := (n - 1)/LP[ n ]; Select[ Range[ 7, 7500 ], PrimeQ[ # ] && CL[ # ] == 4 & ] - Robert G. Wilson v (rgwv(AT)rgwv.com) %Y A056157 Cf. A001913, A097443, A055628, A056210-A056217, A098680 %Y A056157 Sequence in context: A142698 A056209 A098671 this_sequence A142919 A142949 A061664 %Y A056157 Adjacent sequences: A056154 A056155 A056156 this_sequence A056158 A056159 A056160 %K A056157 nonn %O A056157 1,1 %A A056157 Don Willard (dwillard(AT)prairie.cc.il.us), Jun 05 2000 %E A056157 More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 02 2000 Search completed in 0.001 seconds