A369779 a(n) = n * Sum_{p|n, p prime} phi(n/p) / p.

0, 1, 1, 2, 1, 8, 1, 8, 6, 22, 1, 20, 1, 44, 26, 32, 1, 66, 1, 48, 48, 112, 1, 80, 20, 158, 54, 92, 1, 172, 1, 128, 116, 274, 62, 156, 1, 344, 162, 192, 1, 348, 1, 228, 174, 508, 1, 320, 42, 540, 278, 320, 1, 594, 130, 368, 348, 814, 1, 448, 1, 932, 306, 512, 176

Offset

1,4

Links

Antti Karttunen, Table of n, a(n) for n = 1..20000

Mathematica

Table[n*DivisorSum[n, EulerPhi[n/#]/# &, PrimeQ[#] &], {n, 100}]

Prog

(PARI) A369779(n) = if(1==n, 0, my(f=factor(n)); n*sum(i=1, #f~, (eulerphi(n/f[i, 1])/f[i, 1]))); \\ Antti Karttunen, Jan 23 2025

Crossrefs

Cf. A000010, A057660, A117494, A347104, A369687.

Cf. also A369894, A369907, A369909.

Sequence in context: A083529 A102208 A371650 * A379637 A125911 A009385

Adjacent sequences: A369776 A369777 A369778 * A369780 A369781 A369782

Keyword

nonn,easy,changed

Author

Wesley Ivan Hurt, Jan 31 2024

Status

approved