login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A056938 Concatenate all the prime divisors in previous term (with repetition), starting at 49. 8

%I

%S 49,77,711,3379,31109,132393,344131,1731653,71143523,11115771019,

%T 31135742029,717261644891,11193431873899,116134799345907,

%U 3204751189066719,31068250396355573,62161149980213343,336906794442245927,734615161567701999,31318836286194043641

%N Concatenate all the prime divisors in previous term (with repetition), starting at 49.

%C This is the search for the home prime for 49.

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

%H Patrick De Geest, <a href="/A056938/b056938.txt">Table of n, a(n) for n = 1..119</a>

%H P. De Geest, <a href="http://www.worldofnumbers.com/topic1.htm">Home Primes</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/HomePrime.html">Home Prime</a>

%t 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]

%t (* Second program: *)

%t 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 *)

%o (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

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

%K nonn,base

%O 1,1

%A _Robert G. Wilson v_, Sep 05 2000

%E b-file updated by _Max Alekseyev_, Nov 28 2017

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified February 21 14:40 EST 2018. Contains 299414 sequences. (Running on oeis4.)