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 A280712 Inverse Euler transform of A280611. 4
 2, 1, 0, 1, 0, 4, 0, 1, 0, 2, 0, 2, 0, 0, 0, 1, 0, 4, 0, 3, 0, 2, 0, 4, 0, 0, 0, 2, 0, 2, 0, 1, 0, 0, 0, 4, 0, 0, 0, 4, 0, 4, 0, 1, 0, 2, 0, 1, 0, 0, 0, 2, 0, 2, 0, 1, 0, 2, 0, 7, 0, 0, 0, 1, 0, 2, 0, 0, 0, 2, 0, 9, 0, 0, 0, 0, 0, 2, 0, 1, 0, 2, 0, 2, 0, 0, 0, 3, 0, 0, 0, 1, 0, 0, 0, 6, 0, 0, 0, 4, 0, 2, 0, 1, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) = b(n) for n odd, a(n) = b(n) - b(n/2) for n even >= 2, where b(n) = A014197(n) = the number of m with phi(m) = n. Note that a(n) = 0 for all odd n > 1, and so a(n) = b(n) for n >= 3, n not a multiple of 4. LINKS Antti Karttunen, Table of n, a(n) for n = 1..20160 Antti Karttunen, Data supplement: n, a(n) computed for n = 1..100000 FORMULA Euler transform of sequence = Product_{k>=1} (1-x^k)^(-a(k)) is the g.f. of A280611. EXAMPLE a(4) = #{m:phi(m) = 4} - #{m:phi(m) = 2} = #{5,8,10,12} - #{2,4,6} = 4-3 = 1. PROG (PARI) A014197(n, m=1) = { n==1 && return(1+(m<2)); my(p, q); sumdiv(n, d, if( d>=m && isprime(d+1), sum( i=0, valuation(q=n\d, p=d+1), A014197(q\p^i, p))))}; \\ From A014197 A280712(n) = if(n%2, A014197(n), A014197(n)-A014197(n/2)); \\ Antti Karttunen, Nov 09 2018 CROSSREFS Cf. A014197, A280611. Sequence in context: A123022 A072943 A072175 * A306607 A268611 A092147 Adjacent sequences:  A280709 A280710 A280711 * A280713 A280714 A280715 KEYWORD easy,nonn AUTHOR Christopher J. Smyth, Jan 07 2017 EXTENSIONS More terms from Antti Karttunen, Nov 09 2018 STATUS approved

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Last modified August 14 13:12 EDT 2020. Contains 336480 sequences. (Running on oeis4.)