A395181 Values taken by Jordan's totient function J_2, A007434.

1, 3, 8, 12, 24, 48, 72, 96, 120, 144, 168, 192, 216, 288, 360, 384, 504, 528, 576, 600, 648, 768, 840, 864, 960, 1080, 1152, 1344, 1368, 1440, 1536, 1584, 1680, 1728, 1800, 1848, 1944, 2016, 2208, 2304, 2352, 2520, 2808, 2880, 3072, 3456, 3480, 3720, 4032, 4104, 4224, 4320, 4488, 4608

Offset

1,2

Links

Miles Englezou, Table of n, a(n) for n = 1..7248

Example

3 is a term since (2^2-1)*(2^2)^0 = 3.
8 is a term since (3^2-1)*(3^2)^0 = 8.
12 is a term since (2^2-1)*(2^2)^1 = 12.
144 is a term since 3 and 48 are terms, gcd(3, 48) = 1, and 3*48 = 144.

Prog

(PARI) lst(lim)= my(S = Set()); for(n = 1, lim, my(v = n^2); my(f = factor(n)); for(i = 1, #f~, v *= (1 - 1/f[i, 1]^2)); v = numerator(v); if(v <= lim, S = setunion(S, Set([v])))); vecsort(Vec(S))

Crossrefs

Cf. A002202, A007434.

Sequence in context: A379717 A128303 A123906 * A065970 A326890 A024463

Adjacent sequences: A395178 A395179 A395180 * A395182 A395183 A395184

Keyword

nonn

Author

Miles Englezou, Apr 15 2026

Status

approved