A186946 The smallest integer x > 0 such that the number of prime powers p^k (k>=1) in (x/2,x] equals n.

2, 3, 5, 9, 13, 25, 29, 31, 43, 49, 71, 73, 81, 103, 109, 113, 127, 131, 139, 157, 173, 181, 191, 193, 199, 239, 241, 269, 271, 283, 289, 293, 313, 349, 353, 361, 373, 379, 409, 419, 421, 433, 439, 443, 463, 499, 509, 523, 571, 577, 599, 601, 607, 613, 619

Offset

1,1

Comments

An analog of Labos primes (A080359) on prime powers > 1 (A000961).

Links

Peter J. C. Moses, Table of n, a(n) for n = 1..10000

Formula

a(n) <= A186945(n).

Mathematica

a000961Q[n_]:=(Length[FactorInteger[n]]==1) && IntegerQ[n]; nn=99; t=Table[0, {nn+1}]; s=0; Do[If[a000961Q[k], s++]; If[a000961Q[k/2], s--]; If[s<=nn && t[[s+1]]==0, t[[s+1]]=k], {k, 2, Prime[3*nn]}]; Prepend[Rest[t], 2] (* after T. D. Noe's code at A080359 *) (* Peter J. C. Moses, Sep 11 2013 *)

Crossrefs

Cf. A080459, A186945, A228520, A228592.

Sequence in context: A369695 A175125 A171925 * A057225 A309289 A220315

Adjacent sequences: A186943 A186944 A186945 * A186947 A186948 A186949

Keyword

nonn,changed

Author

Vladimir Shevelev, Aug 30 2013

Extensions

More terms from Peter J. C. Moses, Aug 30 2013

Status

approved