A320077 a(n) is smallest positive integer i such that sum of numerator and denominator of sum of j^(-i), when j=1..n, is prime.
1, 1, 1, 1, 1, 2, 1, 3, 1, 1, 1, 2, 34, 1, 1, 5
Offset: 1
Links
- dxdy Blog, MSE Crusher Questioner - will anyone try? (in Russian).
- Math StackExchange, Is there are similar conjecture like this??, Sep 2018.
Crossrefs
Cf. A320076.
Programs
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Mathematica
a[n_] := Do[s = HarmonicNumber[n, r]; If[PrimeQ[Numerator[s] + Denominator[s]], Return[r]], {r, 1, Infinity}]; Table[a[n], {n, 1, 16}] (* Vaclav Kotesovec, Nov 14 2018 *) -
PARI
a(n)={for(i=1, +oo, s=sum(j=1, n, j^(-i)); p=numerator(s); q=denominator(s); if(ispseudoprime(p+q), return(i)))};
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