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

1,1

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.

Prog

(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

Crossrefs

Cf. A000010, A002202.

Cf. A002322, A002174.

Cf. A270265.

Sequence in context: A294310 A048705 A119895 * A255792 A255785 A366740

Adjacent sequences: A270263 A270264 A270265 * A270267 A270268 A270269

Keyword

nonn

Author

Michel Marcus, Mar 14 2016

Status

approved