The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A062095 a(1) = 1, a(n) = concatenation of two closest factors of a(n-1) whose product equals a(n-1) or if a(n-1) is a prime then the concatenation of 1 and a(n-1). 10

%I #9 Mar 22 2023 08:15:31

%S 1,11,111,337,1337,7191,51141,317047,1317047,2814687,9312743,25193697,

%T 30981533,51496017,192326779,1427134777,4987286171,6471777063,

%U 61653104971,259323776747,737046253821,7171027958513,31727922601647

%N a(1) = 1, a(n) = concatenation of two closest factors of a(n-1) whose product equals a(n-1) or if a(n-1) is a prime then the concatenation of 1 and a(n-1).

%H Sean A. Irvine, <a href="/A062095/b062095.txt">Table of n, a(n) for n = 1..250</a>

%e a(3) = 111 hence a(4) = 337, as 3*37 = 111 and 3 < 37.

%t f[n_Integer] := (d = Divisors[n]; l = Length[d]; If[ EvenQ[l], ToExpression[ ToString[ d[[l/2]] ] <> ToString[ d[[l/2 + 1]] ]], ToExpression[ ToString[d[[l/2 + .5]] ] <> ToString[ d[[l/2 + .5]] ]]] ); NestList[f, 1, 25]

%Y Cf. A062094, A003681.

%K nonn,easy,base

%O 1,2

%A _Amarnath Murthy_, Jun 16 2001

%E More terms from _Robert G. Wilson v_, Aug 08 2001

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

Last modified September 26 14:24 EDT 2023. Contains 365660 sequences. (Running on oeis4.)