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A245315 Concatenate n-th composite number with concatenation of its prime factors in ascending order. 3
422, 623, 8222, 933, 1025, 12223, 1427, 1535, 162222, 18233, 20225, 2137, 22211, 242223, 2555, 26213, 27333, 28227, 30235, 3222222, 33311, 34217, 3557, 362233, 38219, 39313, 402225, 42237, 442211, 45335, 46223, 4822223 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Jens Kruse Andersen, Table of n, a(n) for n = 1..10000

EXAMPLE

a(1)=422 since 4=2*2 and 4 is the first composite integer.

MATHEMATICA

f[n_]:=FactorInteger[n]; con[A_]:=(v1={}; l=Length[A]; Do[v1=Join[v1, IntegerDigits[A[[k]]]], {k, l}]; FromDigits[v1]); alfa[n_]:=(b=f[n]; j=Length[b]; c=Table[Table[b[[k]][[1]], {b[[k]][[2]]}], {k, j}]; w={}; Do[w=Join[w, c[[k]]], {k, j}]; con[w]); na[n_]:=con[{n, alfa[n]}]; v=Select[Range[2, 1000], !PrimeQ[#]&]; Table[na[v[[k]]], {k, 32}]

ncpf[n_]:=FromDigits[Join[IntegerDigits[n], Flatten[IntegerDigits/@Table[ #[[1]], #[[2]]]&/@FactorInteger[n]]]]; ncpf/@Select[Range[ 100], CompositeQ] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 03 2019 *)

CROSSREFS

Cf. A002808, A245316.

Sequence in context: A303334 A109505 A109473 * A200200 A231585 A231837

Adjacent sequences:  A245312 A245313 A245314 * A245316 A245317 A245318

KEYWORD

nonn,base

AUTHOR

Jahangeer Kholdi, Sep 15 2014

STATUS

approved

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Last modified August 12 20:18 EDT 2022. Contains 356077 sequences. (Running on oeis4.)