A328724 a(1)=2, a(2)=3; a(n) is the smallest k > a(n-1) such that k + a(n-1) is a multiple of a(n-2).

2, 3, 5, 7, 8, 13, 19, 20, 37, 43, 68, 104, 168, 248, 256, 488, 536, 928, 1216, 1568, 2080, 2624, 3616, 4256, 6592, 10432, 15936, 25792, 37952, 39424, 74432, 83264, 140032, 193024, 227072, 352000, 556288, 851712, 1373440, 2033408, 2086912, 4013312

Offset

1,1

Comments

(a(n+1)+a(n+2))/a(n) gives the sequence 4, 4, 3, 3, 4, 3, 3, 4, 3, 4, 4, 4, 3, 3, 4, 3, 4, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 3, 3, 4, 3, 4, 3, 3, 4, 4, 4, 4, 3, 3, 4, 3, 4, 3, 3, 3, 4, 3, ...

Links

Robert Israel, Table of n, a(n) for n = 1..6866

Example

a(7)=19; a(8)=20. 37 is the smallest number, larger than 20, that can be added to 20 and the result (57) is divisible by 19. So, a(9)=37.

Maple

A[1]:= 2: A[2]:= 3:
for n from 3 to 50 do
  k:= -A[n-1] mod A[n-2];
  A[n]:= k + A[n-2]*(1+floor((A[n-1]-k)/A[n-2]));
od:
seq(A[i], i=1..50); # Robert Israel, Oct 27 2019

Crossrefs

Sequence in context: A080435 A108330 A262587 * A039892 A278645 A352290

Adjacent sequences: A328721 A328722 A328723 * A328725 A328726 A328727

Keyword

nonn

Author

Ali Sada, Oct 26 2019

Status

approved