Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #15 Jan 16 2021 06:40:02
%S 42,70,154,176,182,238,266,322,406,434,518,574,602,658,742,826,854,
%T 938,994,1022,1106,1162,1246,1250,1358,1414,1442,1498,1526,1582,1664,
%U 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
%N Positions of seventeens in A340094, the Dirichlet inverse of f(n) = n - phi(n) + 1.
%C These terms correspond to the horizontal line shown above the X-axis in the logarithmic scatter plots of A340094.
%C 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}.
%H Antti Karttunen, <a href="/A340384/b340384.txt">Table of n, a(n) for n = 1..13832; all terms < 2^21</a>
%F {n such that A340094(n) = 17}.
%o (PARI) isA340384(n) = (17==A340094(n));
%Y Cf. A065091, A340094.
%K nonn
%O 1,1
%A _Antti Karttunen_, Jan 07 2021