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A182759 a(1) = 1, a(2) = 3, for n >= 3; a(n) = the smallest number h > a(n-1) such that [[a(n-2) + a(n-1)] * [a(n-2) + h] * [a(n-1) + h]] / [a(n-2) + a(n-1) + h] is integer. 2
1, 3, 8, 11, 19, 25, 32, 38, 42, 53, 64, 75, 101, 124, 147, 163, 179, 195, 289, 296, 299, 315, 352, 368, 384, 720, 736, 752, 768, 912, 980, 1034, 1066, 1098, 2100, 2132, 2164, 2196, 2289, 2382 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..10000

EXAMPLE

For n = 5; a(3) = 8, a(4) = 11, a(5) = 19 before [(8+11)*(8+19)*(11+19)]  / (8+11+19) = 405 (integer).

MATHEMATICA

nxt[{a_, b_}]:= Module[{h = b + 1}, While[! IntegerQ[((a + b) (a + h) (b + h))/(a + b + h)], h++]; {b, h}]; Transpose[NestList[nxt, {1, 3}, 100]][[1]] (* G. C. Greubel, Jan 23 2018 *)

CROSSREFS

Cf. A182758.

Sequence in context: A154485 A105410 A114548 * A022121 A171672 A070073

Adjacent sequences:  A182756 A182757 A182758 * A182760 A182761 A182762

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Nov 28 2010

STATUS

approved

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Last modified May 31 02:51 EDT 2020. Contains 334747 sequences. (Running on oeis4.)