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A037276 Start with 1; for n>1, replace n with the concatenation of its prime factors in increasing order. 15
1, 2, 3, 22, 5, 23, 7, 222, 33, 25, 11, 223, 13, 27, 35, 2222, 17, 233, 19, 225, 37, 211, 23, 2223, 55, 213, 333, 227, 29, 235, 31, 22222, 311, 217, 57, 2233, 37, 219, 313, 2225, 41, 237, 43, 2211, 335, 223, 47, 22223, 77, 255, 317, 2213, 53, 2333 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

T. D. Noe, Table of n, a(n) for n=1..10000

P. De Geest, Home Primes

Eric Weisstein's World of Mathematics, More info (2)

EXAMPLE

If n=2^3*5^5*11^2 = 3025000, a(n) = 222555551111 (n=2*2*2*5*5*5*5*5*11*11, then remove the multiplication signs).

MAPLE

read("transforms") ;

A037276 := proc(n)

    local L, p ;

    L := [] ;

    for p in ifactors(n)[2] do

        L := [op(L), seq(op(1, p), i=1..op(2, p))] ;

    end do:

    digcatL(L) ;

end proc: # R. J. Mathar, Oct 29 2012

MATHEMATICA

co[n_, k_] := Nest[Flatten[IntegerDigits[{#, n}]] &, n, k - 1]; Table[FromDigits[Flatten[IntegerDigits[co @@@ FactorInteger[n]]]], {n, 54}] (* Jayanta Basu, Jul 04 2013 *)

FromDigits@ Flatten@ IntegerDigits[Table[#1, {#2}] & @@@ FactorInteger@ #] & /@ Range@ 54 (* Michael De Vlieger, Jul 14 2015 *)

PROG

(PARI) a(n)={ n<4 & return(n); for(i=1, #n=factor(n)~, n[1, i]=concat(vector(n[2, i], j, Str(n[1, i])))); eval(concat(n[1, ]))}  \\ M. F. Hasler, Jun 19 2011

(Haskell)

a037276 = read . concatMap show . a027746_row

-- Reinhard Zumkeller, Apr 03 2012

CROSSREFS

Cf. A037274, A048985, A067599, A080670, A084796. Different from A073646.

Cf. A027746.

Sequence in context: A080670 A073647 A073646 * A068190 A084796 A084797

Adjacent sequences:  A037273 A037274 A037275 * A037277 A037278 A037279

KEYWORD

nonn,easy,base

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified May 23 08:43 EDT 2017. Contains 286909 sequences.