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A087874 a[n] =PrimePi[PrimePi[n-1]] + a[n - a[n-1]] 0
1, 1, 1, 2, 2, 4, 3, 4, 4, 6, 4, 7, 7, 6, 7, 7, 9, 8, 8, 11, 10, 11, 11, 11, 10, 11, 11, 13, 11, 12, 12, 16, 14, 16, 13, 16, 15, 16, 16, 16, 15, 17, 17, 17, 19, 17, 18, 18, 18, 22, 17, 19, 22, 22, 20, 22, 19, 22, 21, 23, 23, 23, 23, 22, 24, 24, 24, 25, 25, 27, 25, 26, 26, 26, 26, 30 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

A reinversion type sequence using the distribution sequence of the primes as the inverse function and A004001 as the pattern function.

Frequency count shows this sequence doesn't cover the integer domain.

LINKS

Table of n, a(n) for n=1..76.

MATHEMATICA

crid[n_Integer?Positive] := crid[n] =PrimePi[PrimePi[n-1]] + crid[n - crid[n-1]] crid[1] = crid[2] = 1 digits=256 a=Table[crid[n], {n, 1, digits}]

CROSSREFS

Cf. A004001.

Sequence in context: A217754 A319397 A094950 * A166267 A117484 A086835

Adjacent sequences:  A087871 A087872 A087873 * A087875 A087876 A087877

KEYWORD

nonn

AUTHOR

Roger L. Bagula, Oct 11 2003

STATUS

approved

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Last modified March 3 03:03 EST 2021. Contains 341756 sequences. (Running on oeis4.)