login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A280692 a(n) = A003961(n) - A250469(n). 4

%I

%S 0,0,0,0,0,0,0,6,0,-6,0,12,0,-6,0,36,0,24,0,6,0,-24,0,66,0,-24,60,18,

%T 0,18,0,150,-20,-42,0,120,0,-42,-10,72,0,42,0,-12,60,-48,0,264,0,0,

%U -30,0,0,216,0,132,-30,-78,0,138,0,-72,120,540,0,0,0,-30,-30,24,0,462,0,-96,60,-18,0,24,0,330,420,-114,0,246

%N a(n) = A003961(n) - A250469(n).

%H Antti Karttunen, <a href="/A280692/b280692.txt">Table of n, a(n) for n = 1..10067</a>

%F a(n) = A003961(n) - A250469(n).

%t f[n_] := f[n] = Which[n == 1, 1, PrimeQ@ n, NextPrime@ n, True, Times @@ Replace[FactorInteger[n], {p_, e_} :> f[p]^e, 1]]; g[n_] := If[n == 1, 0, PrimePi@ FactorInteger[n][[1, 1]]]; Function[s, MapIndexed[ Function[{m, n}, f@ n - Lookup[s, g[n] + 1][[m]] + Boole[n == 1]][#1, First@ #2] &, #] &@ Map[Position[Lookup[s, g@ #], #][[1, 1]] &, Range@ 120]]@ PositionIndex@ Array[g, 10^4]] (* _Michael De Vlieger_, Mar 09 2017, Version 10 *)

%o (Scheme) (define (A280692 n) (- (A003961 n) (A250469 n)))

%Y Cf. A003961, A250469, A249820, A280492, A280497, A280498, A280702.

%Y Cf. A280693 (gives the positions of zeros).

%Y Cf. also arrays A083221 and A246278.

%K sign

%O 1,8

%A _Antti Karttunen_, Mar 08 2017

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 15 02:19 EDT 2019. Contains 327062 sequences. (Running on oeis4.)