Search: id:A068563 Results 1-1 of 1 results found. %I A068563 %S A068563 1,2,4,6,8,12,16,18,20,24,32,36,40,42,48,54,60,64,72,80,84,96,100,108, %T A068563 120,126,128,136,144,156,160,162,168,180,192,200,216,220,240,252,256, %U A068563 272,288,294,300,312,320,324,336,342,360,378,384,400,408,420,432,440 %N A068563 Numbers n such that 2^n (mod n) = 4^n (mod n). %C A068563 If k is in the sequence then 2k is also in the sequence, but the converse is not true. %C A068563 Almost the same as A124240, numbers n such that lambda(n) divides n, where lambda(n) is Carmichael's lambda function, A002322. - T. D. Noe (noe(AT)sspectra.com), May 30 2003 %H A068563 T. D. Noe, Table of n, a(n) for n = 1..1000 %H A068563 Eric Weisstein's World of Mathematics, Carmichael Function %t A068563 Select[Range[500], PowerMod[2,#,# ] == PowerMod[4,#,# ] & ] %Y A068563 Cf. A002322. %Y A068563 Sequence in context: A125225 A092903 A005153 this_sequence A124240 A068997 A067712 %Y A068563 Adjacent sequences: A068560 A068561 A068562 this_sequence A068564 A068565 A068566 %K A068563 easy,nonn %O A068563 1,2 %A A068563 Benoit Cloitre (benoit7848c(AT)orange.fr), Mar 25 2002 %E A068563 Comment and Mathematica program corrected by T. D. Noe (noe(AT)sspectra.com), Oct 17 2008 Search completed in 0.004 seconds