A087884 a(n) = PrimePi[PrimePi[n-1]] + Prime[Abs[n - Prime[n-1]]]

3, 4, 13, 15, 25, 31, 43, 63, 70, 92, 106, 110, 130, 154, 183, 185, 215, 233, 237, 267, 281, 315, 357, 377, 383, 401, 405, 425, 504, 526, 568, 574, 622, 624, 658, 688, 714, 748, 779, 793, 859, 863, 883, 887, 973, 1039, 1057, 1067, 1093, 1115, 1123, 1199

Offset

4,1

Comments

A prime based reinversion sequence based on the A004001 pattern.

Links

Table of n, a(n) for n=4..55.

Mathematica

prid[n_Integer?Positive] := prid[n] =PrimePi[PrimePi[n-1]] + Prime[Abs[n - Prime[n-1]]] prid[1] = prid[2] = 1 digits=256 a=Table[prid[n], {n, 4, digits+4}]

Crossrefs

Cf. A004001.

Sequence in context: A208847 A278426 A293280 * A057570 A024853 A023857

Adjacent sequences: A087881 A087882 A087883 * A087885 A087886 A087887

Keyword

nonn

Author

Roger L. Bagula, Oct 12 2003

Status

approved