A145584 - OEIS

A145584

a(n) = number of numbers removed in step n of Eratosthenes's sieve for 2^6.

31, 10, 3, 1

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OFFSET

1,1

COMMENTS

Number of steps in Eratosthenes's sieve for 2^n is A060967(n).

Number of primes less than 2^6 is equal to 2^6 - (sum all of numbers in this sequence) - 1 = A007053(6).

LINKS

Table of n, a(n) for n=1..4.

MATHEMATICA

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 = 6; kk = PrimePi[Sqrt[2^nn]]; t3 = f3[2^nn, kk] (* Bob Hanlon (hanlonr(AT)cox.net) *)

CROSSREFS

Cf. A006880, A122121.

Cf. A145532, A145533, A145534, A145535, A145536, A145537, A145538, A145539, A145540.

Cf. A145583, A145584, A145585, A145586, A145587, A145588, A145589, A145590, A145591, A145592.

Sequence in context: A040936 A029821 A040935 * A178561 A065821 A040934

Adjacent sequences: A145581 A145582 A145583 * A145585 A145586 A145587

KEYWORD

fini,full,nonn

AUTHOR

Artur Jasinski with assistance from Bob Hanlon (hanlonr(AT)cox.net), Oct 14 2008

STATUS

approved