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A324340 a(n) = A046692(A005940(1+n)), where A005940 is the Doudna sequence and A046692 is the Dirichlet inverse of sigma function. 4
1, -3, -4, 2, -6, 12, 3, 0, -8, 18, 24, -8, 5, -9, 0, 0, -12, 24, 32, -12, 48, -72, -18, 0, 7, -15, -20, 6, 0, 0, 0, 0, -14, 36, 48, -16, 72, -96, -24, 0, 96, -144, -192, 48, -40, 54, 0, 0, 11, -21, -28, 10, -42, 60, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, -18, 42, 56, -24, 84, -144, -36, 0, 112, -216, -288, 64, -60, 72, 0, 0, 168, -288, -384, 96, -576, 576, 144, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
FORMULA
a(n) = A046692(A005940(1+n)).
PROG
(PARI) A324340(n) = { my(m1=1, p=2); while(n, if(!(n%2), p=nextprime(1+p); n>>=1, if(1==(n%4), m1 *= -(1+p), if(3==(n%8), m1 *= p, return(0))); while((n%2), n>>=1))); (m1); };
(PARI)
A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t }; \\ From A005940
A046692(n) = { my(f=factor(n)~); prod(i=1, #f, if(1==f[2, i], -(f[1, i]+1), if(2==f[2, i], f[1, i], 0))); };
A324340(n) = A046692(A005940(1+n));
CROSSREFS
Sequence in context: A243256 A269868 A344968 * A046692 A205769 A166108
KEYWORD
sign
AUTHOR
Antti Karttunen, Feb 24 2019
STATUS
approved

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Last modified May 21 12:49 EDT 2024. Contains 372736 sequences. (Running on oeis4.)