[seqfan] Slight error in [Koshy, 2001], corrected in OEIS but not mentioned

Alonso Del Arte alonso.delarte at gmail.com
Wed Sep 8 01:39:43 CEST 2010

Don't know if this matters at all, but in Thomas Koshy's book on Fibonacci
and Lucas numbers, the formula for even-indexed Lucas numbers in terms of
squares of Lucas numbers (A001254) is erroneously given as L(2n) = 2L(n)^2 +
2(-1)^(n - 1) on page 404 as Identity 34.7. Just a little bit later on the
same page, there is the correct deduction L(r)^2 +/- 2. The OEIS gives the
correct formula L(2n) + 2(-1)^n but makes no mention of the mistake in
Koshy's book.


P.S. That error I found while researching the Lucas multiplication table
which Daniel asked me about; that table is the very first sequence this year
I've considered worth submitting (which I did just a short while ago).

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