A096354 Integer part of the fourth nesting of the logarithmic integral of 10^n.

2, 4, 9, 19, 51, 177, 747, 3638, 19691, 115237, 716530, 4675989, 31744547, 222714791, 1606590368, 11868687555, 89506353843, 687275943030, 5361745095952, 42423407975227, 339921277226567, 2754682467870463, 22553369649557926, 186375668569345609

Offset

1,1

Comments

m=4 in PARI below. With nesting level 7, z < 1 and Li(z) is not defined so an error occurs. This is why we take the absolute value of Li(z).

Links

Table of n, a(n) for n=1..24.

Formula

Let Li(n) = logarithmic integral of n. a(n) = Li(Li(Li(Li(n))))

Mathematica

Floor[Nest[LogIntegral, 10^Range[30], 4]] (* Harvey P. Dale, Jun 18 2013 *)

Prog

(PARI) g(n, m) = for(x=1, n, z=10^x; for(y=1, m, z=abs(Li(z))); print1(floor(z)", ")) Li(x) = { -eint1(log(1/x)) }

Crossrefs

Sequence in context: A076893 A176501 A324317 * A076838 A034749 A353734

Adjacent sequences: A096351 A096352 A096353 * A096355 A096356 A096357

Keyword

nonn

Author

Cino Hilliard, Jun 30 2004

Extensions

More terms from Harvey P. Dale, Jun 18 2013

Status

approved