A088364 a(n) = index of the n-th local minimum of A053707.
1, 3, 6, 9, 13, 16, 19, 21, 26, 28, 30, 33, 37, 39, 43, 48, 50, 53, 56, 61, 63, 66, 68, 70, 73, 75, 78, 80, 82, 86, 90, 94, 96, 98, 102, 105, 108, 112, 115, 119, 124, 128, 132, 134, 136, 139, 141, 144, 146, 148, 150, 152, 156, 158, 160, 165, 168, 171, 173, 176, 180, 182
Offset: 1
Keywords
Examples
The eighth local minimum of A053707 is 17 and occurs at index 21, hence a(8) = 21; A053707(a(8)) = A053707(21) = 17 = A088363(8).
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
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Maple
N:= 10^6: # to use values of A025475 up to N P:= select(isprime, [2,seq(i,i=3..isqrt(N),2)]): B:= sort([1,seq(seq(p^i,i=2..ilog[p](N)),p=P)]): DB:= B[2..-1]-B[1..-2]: T:= select(t -> DB[t] <= DB[t-1] and DB[t] <= DB[t+1], [$2..nops(DB)-1]): [1,op(T)]; # Robert Israel, Aug 21 2023
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PARI
{m=1; k=0; for(n=2,530000,if(matsize(factor(n))[1]==1&&factor(n)[1,2]>1,d=n-m; if((k<2||b>c)&&(!k<1&&d>=c),print1(k,",")); k++; m=n; b=c; c=d))}
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