A051479 Values of i such that phi(x) = 4i+2 has 4 solutions.
1, 4, 10, 40, 121, 364, 1105, 1540, 3601, 4795, 5662, 6601, 9841, 19414, 35815, 103201, 131950, 141224, 210910, 245272, 378532, 505876, 613480, 762565, 986545, 1010527, 1147576, 1252720, 1732847, 1750990, 1766905, 1798951, 1863907, 2337352, 2674042, 2773057, 3080902
Offset: 1
Keywords
Examples
phi(x) = 4*1+2 has 4 solutions (x = 7,9,14,18), so 1 is in the sequence.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..210
- Max Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems (invphi.gp).
Programs
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PARI
is(k) = invphiNum(4*k+2) == 4; \\ Amiram Eldar, Nov 05 2024, using Max Alekseyev's invphi.gp
Extensions
a(33)-a(37) from Amiram Eldar, Nov 05 2024