1,1

Number of steps in Eratosthenes' sieve for 10^n is A122121(n).

Number of primes less than 10^2 is equal = 10^2 - (sum all of numbers in this sequence) - 1 = A006880(2).

f3[k_Integer?Positive, i_Integer?Positive] := Module[{f, m, r, p}, p = Transpose[{r = Range[2, i], Prime[r]}]; f[x_] := Catch[Fold[If[Mod[x, #2[[2]]] == 0, Throw[m[ #2[[1]]] = m[ #2[[1]]] + 1], #1] &, If[Mod[x, 2] == 0, Throw[m[1] = m[1] + 1]], p]]; Table[m[n] = -1, {n, i}]; f /@ Range[k]; Table[m[n], {n, i}]]; nn = 2; kk = PrimePi[Sqrt[10^nn]]; t3 = f3[10^nn, kk] (*Bob Hanlon*)

A006880, A122121, A145532-A145540, A145583-A145592

Sequence in context: A115480 A005071 A012120 this_sequence A065787 A033369 A027647

Adjacent sequences: A145580 A145581 A145582 this_sequence A145584 A145585 A145586

fini,nonn

Artur Jasinski with assistence from Bob Hanlon (grafix(AT)csl.pl), Oct 14 2008