A051478 a(n) is the number of values k satisfying phi(k) = 4*n+2, n>0.

4, 2, 0, 4, 2, 0, 2, 0, 0, 4, 2, 0, 2, 2, 0, 2, 2, 0, 2, 2, 0, 0, 0, 0, 2, 2, 2, 0, 0, 0, 2, 2, 0, 2, 0, 0, 2, 0, 0, 4, 2, 0, 0, 2, 0, 0, 2, 0, 2, 0, 0, 2, 0, 0, 2, 2, 0, 0, 2, 0, 0, 2, 0, 0, 2, 0, 2, 0, 0, 2, 0, 0, 2, 0, 0, 2, 2, 0, 0, 0, 0, 2, 0, 0, 2, 2, 0, 0, 2, 0, 2, 0, 0, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0

Offset

1,1

Comments

Sequence consists of only 0's, 2's and 4's.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Max Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems (invphi.gp).

Example

phi(k) = 4*1+2 has 4 solutions (k = 7, 9, 14, 18), so a(1) = 4.

Prog

(PARI) a(n) = invphiNum(4*n+2); \\ Amiram Eldar, Nov 05 2024, using Max Alekseyev's invphi.gp

Crossrefs

Cf. A000010, A032446, A051479.

Sequence in context: A048819 A076114 A294666 * A121829 A021708 A016690

Adjacent sequences: A051475 A051476 A051477 * A051479 A051480 A051481

Keyword

nonn

Author

Jud McCranie

Status

approved