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A246063 First occurrence of n in sequence A112329. 2
2, 1, 3, 9, 15, 64, 45, 256, 96, 144, 192, 4096, 240, 16384, 768, 576, 480, 262144, 720, 1048576, 960, 2304, 12288, 16777216, 1440, 5184, 49152, 3600, 3840, 1073741824, 2880, 4294967296, 3360, 36864, 786432, 20736, 5040, 274877906944, 3145728, 147456, 6720 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Inspired by a comment from Robert G. Wilson v in sequence A112329.

LINKS

Ray Chandler, Table of n, a(n) for n = 0..3322 [terms <= 1000 digits]

FORMULA

a(p) = 2^(p+1) for prime p >= 5.

MATHEMATICA

g[lst_, p_]:=Module[{t, i, j}, Union[Flatten[Table[t=lst[[i]]; t[[j]]=p*t[[j]]; Sort[t], {i, Length[lst]}, {j, Length[lst[[i]]]}], 1], Table[Sort[Append[lst[[i]], p]], {i, Length[lst]}]]]; f[n_]:=Module[{i, j, p, e, lst={{}}}, {p, e}=Transpose[FactorInteger[n]]; Do[lst=g[lst, p[[i]]], {i, Length[p]}, {j, e[[i]]}]; lst];

(* above factor functions from T. D. Noe in A162247 *)

nmax=100;

a1={2, 1, 3};

Do[

least=Infinity;

fn=f[n];

Do[

exps=Reverse[fnitem]-1;

odd=even=1;

cnt=0;

Do[

cnt++;

odd*=(Prime[cnt+1]^exp);

even*=(Prime[cnt]^exp);

, {exp, exps}];

least=Min[least, odd, 4even];

, {fnitem, fn}];

AppendTo[a1, least];

, {n, 3, nmax}];

a1

PROG

(PARI) d(n) = if (denominator(n)==1, numdiv(n), 0);

f(n) = numdiv(n) - 2*d(n/2) + 2*d(n/4);

a(n) = {my(k = 1); while (f(k) != n, k++); k; } \\ Michel Marcus, Jul 30 2017

CROSSREFS

Cf. A094572, A112329.

Sequence in context: A249632 A126009 A301282 * A229417 A260758 A091858

Adjacent sequences:  A246060 A246061 A246062 * A246064 A246065 A246066

KEYWORD

nonn

AUTHOR

Ray Chandler, Aug 24 2014

STATUS

approved

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Last modified June 24 21:16 EDT 2019. Contains 324337 sequences. (Running on oeis4.)