OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
William D. Banks and Igor E. Shparlinski, Average value of the Euler function on binary palindromes, Bulletin of the Polish Academy of Sciences, Mathematics, Vol. 54, No. 2 (2006), pp. 95-101; alternative link.
FORMULA
MATHEMATICA
EulerPhi[Select[Range[5000], EvenQ[Length[(d = IntegerDigits[#, 2])]] && PalindromeQ[d] &]]
PROG
(PARI) is(n) = Vecrev(n = binary(n)) == n && !((#n)%2);
lista(kmax) = for(k = 1, kmax, if(is(k), print1(eulerphi(k), ", ")));
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Amiram Eldar, Mar 16 2024
STATUS
approved