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A088364
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a(n) = index of the n-th local minimum of A053707.
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2
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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
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OFFSET
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1,2
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LINKS
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FORMULA
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EXAMPLE
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MAPLE
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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]):
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PROG
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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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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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