A339973 Numbers k for which A019565(2k)-1 is a multiple of A000265(phi(A019565(2k))).

0, 1, 2, 3, 4, 8, 16, 20, 32, 33, 34, 35, 38, 41, 50, 56, 64, 128, 176, 256, 259, 290, 512, 1024, 2048, 2056, 2081, 2089, 2096, 2180, 4096, 4130, 8192, 9218, 16384, 18436, 32768, 65536, 131072, 131140, 262144, 279552, 524288, 524308, 524546, 1048576, 1048736, 2097152, 4194304, 4194352, 4194420, 4196656, 4202499, 8388608

Offset: 1

Author

Antti Karttunen, Dec 26 2020

Keywords

• nonn

Comments

Numbers k such that A339971(k) divides A339809(2k).

Union of {0}, A000079 and the terms of (1/2)*A048675(A339880(i)), for i >= 1, sorted into ascending order.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..94

Crossrefs

Positions of zeros in A339898, and of ones in A339901.

Cf. A000010, A000265, A048675, A339821, A339880, A339809, A339971, A339974.

Cf. A000079 (subsequence).

Cf. also A339816, A339906.

Programs

PARI

A019565(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= p); n >>= 1); (m); };
isA339971(n) = { my(x=A019565(2*n)); !((x-1)%A000265(eulerphi(x))); };