A270266 Numbers that are values of the reduced totient function (A002174) but not of the totient function (A002202).
90, 174, 230, 234, 246, 290, 308, 318, 364, 390, 410, 414, 450, 510, 516, 530, 534, 572, 594, 638, 644, 666, 678, 680, 702, 714, 728, 740, 770, 804, 830, 846, 870, 890, 902, 948, 954, 1026, 1036, 1074, 1098, 1100, 1110, 1130, 1134, 1146, 1148, 1164, 1166, 1190, 1204
Offset: 1
Keywords
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
- William D. Banks, John B. Friedlander, Florian Luca, Francesco Pappalardi, and Igor E. Shparlinski, Coincidences in the values of the Euler and Carmichael functions, Acta Arithmetica 122 (2006), 207-234.
Programs
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PARI
isA002174(n) = if(n%2, return(n==1)); my(f=factor(n), pe); for(i=1, #f~, if(n%(f[i, 1]-1)==0, next); pe=f[i, 1]^f[i, 2]; forstep(q=2*pe+1, n+1, 2*pe, if(n%(q-1)==0 && isprime(q), next(2))); return(0)); 1 \\ Charles R Greathouse IV at A002174 is(n) = !istotient(n) && isA002174(n); \\ Amiram Eldar, Dec 01 2024