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A056938 Concatenate all the prime divisors in previous term (with repetition), starting at 49. 8
49, 77, 711, 3379, 31109, 132393, 344131, 1731653, 71143523, 11115771019, 31135742029, 717261644891, 11193431873899, 116134799345907, 3204751189066719, 31068250396355573, 62161149980213343, 336906794442245927, 734615161567701999, 31318836286194043641 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This sequence provides a record of the search for the home prime for 49.

This sequence has now been followed for 117 steps without a prime being reached (after which of course it would simply repeat).

LINKS

Patrick De Geest, Table of n, a(n) for n = 1..119

P. De Geest, Home Primes

Eric Weisstein's World of Mathematics, Home Prime

MATHEMATICA

g[n_] := (x = n; d = {}; While[FactorInteger[x] != {}, f = FactorInteger[x, FactorComplete -> True][[1, 1]]; x = x/f; AppendTo[d, IntegerDigits[f]]]; FromDigits[Flatten[d]]); NestList[g, 49, 25]

(* Second program: *)

NestList[FromDigits@ Flatten@ Map[IntegerDigits, FactorInteger[#] /. {p_, e_} /; p >= 1 :> If[p == 1, 1, ConstantArray[p, e]]] &, 49, 16] (* Michael De Vlieger, Apr 27 2017 *)

PROG

(PARI) a=vector(35); a[1]=49; for(k=2, length(a), f=factor(a[k-1]); for(i=1, matsize(f)[1], l=10^ceil(log(f[i, 1])/log(10)); for(j=1, f[i, 2], a[k]=a[k]*l+f[i, 1]))) \\ M. F. Hasler, Mar 09 2007

CROSSREFS

Cf. A006919, A037273, A037274, A037271, A238579.

Sequence in context: A103216 A036307 A294028 * A267986 A207638 A286095

Adjacent sequences:  A056935 A056936 A056937 * A056939 A056940 A056941

KEYWORD

nonn,base

AUTHOR

Robert G. Wilson v, Sep 05 2000

EXTENSIONS

b-file updated by Max Alekseyev, Nov 28 2017

STATUS

approved

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Last modified July 17 17:07 EDT 2018. Contains 312721 sequences. (Running on oeis4.)