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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A308527 Numbers that, for some x, are the concatenation of x+2, x+1 and x and are divisible by at least two of x+2, x+1 and x. 2
 321, 432, 121110, 171615, 343332, 118117116, 232231230, 334333332, 333433333332, 452245214520, 333343333333332, 333334333333333332, 333333433333333333332, 333333343333333333333332 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS For each d>=1, (10^(3*d)-4)/3+10^(2*d) (the concatenation of x+2, x+1 and x where x = (10^d-4)/3) is in the sequence, being divisible by x+1 and x+3. Thus the sequence is infinite. It appears that a(n) is of the form (10^(3*d)-4)/3+10^(2*d) for n >= 11. - Chai Wah Wu, Jun 19 2019 LINKS Chai Wah Wu, Table of n, a(n) for n = 1..56 EXAMPLE 232231230 is the concatenation of 232, 231 and 230, and is divisible by 231 and 230, so it is in the sequence. MAPLE f:= proc(x) local t1, t2, q, a, b; t1:= 10^length(x); t2:= t1*10^length(x+1); q:= x*(1+t1+t2)+2*t2+t1; a:= (q/x)::integer; b:= (q/(x+1))::integer; if a and b then return q elif not(a) and not(b) then return NULL fi; if (q/(x+2))::integer then q else NULL fi end proc: map(f, [\$1..10^8]); CROSSREFS Cf. A306643. Subsequence of A127424. Sequence in context: A300849 A351994 A261262 * A268517 A228226 A004927 Adjacent sequences: A308524 A308525 A308526 * A308528 A308529 A308530 KEYWORD nonn,base AUTHOR J. M. Bergot and Robert Israel, Jun 05 2019 STATUS approved

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 June 9 00:10 EDT 2023. Contains 363165 sequences. (Running on oeis4.)