A340384 Positions of seventeens in A340094, the Dirichlet inverse of f(n) = n - phi(n) + 1.

42, 70, 154, 176, 182, 238, 266, 322, 406, 434, 518, 574, 602, 658, 742, 826, 854, 938, 994, 1022, 1106, 1162, 1246, 1250, 1358, 1414, 1442, 1498, 1526, 1582, 1664, 1778, 1834, 1918, 1946, 2086, 2114, 2198, 2282, 2338, 2422, 2506, 2534, 2674, 2702, 2758, 2786, 2954, 3122, 3178, 3206, 3262, 3346, 3374, 3514, 3598

Offset: 1

Author

Antti Karttunen, Jan 07 2021

Keywords

• nonn

Comments

These terms correspond to the horizontal line shown above the X-axis in the logarithmic scatter plots of A340094.

The only non-multiples of 7 among the first 13832 terms are 176, 1250, 1664. Apart from such exceptions (are there more?), all other terms are of the form 2*7*p, with p running through all odd primes in A065091 \ {7}.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..13832; all terms < 2^21

Crossrefs

Cf. A065091, A340094.

Programs

PARI

isA340384(n) = (17==A340094(n));

Formula

{n such that A340094(n) = 17}.