OFFSET
1,1
COMMENTS
EXAMPLE
uphi(14307856) = uphi(14307855) + uphi(14307854) (3366080 = 7102080 + 6264000), so 14307856 is in the sequence.
MATHEMATICA
uphi[n_]:=If[n == 1, 1, (Times@@(Table[#[[1]]^#[[2]]-1, {1}] & /@ FactorInteger[n]))[[1]]]; Select[ Range[3, 10^6], uphi[#] == uphi[#-1] + uphi[#-2] &]
PROG
(PARI) uphi(n) = my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2]-1);
isok(n) = uphi(n)==uphi(n-1)+uphi(n-2); \\ Altug Alkan, Sep 08 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Sep 07 2017
EXTENSIONS
a(18)-a(26) from Amiram Eldar, Mar 01 2020
STATUS
approved