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A069970 Numbers n such that sigma(reverse(n)) = sigma(reverse(n-1)) + sigma(reverse(n-2)). 0
3, 4, 352, 525, 532, 564, 572, 782, 3783, 5242, 5762, 5784, 7852, 7884, 31732, 38817, 41736, 46194, 52942, 57842, 61146, 63075, 67266, 68853, 95418 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
sigma(reverse(352)) = sigma(253) = 288 = 234 + 54 = sigma(153) + sigma(53) = sigma(reverse(352-1)) + sigma(reverse(352-2)).
MATHEMATICA
rev[n_] := FromDigits[Reverse[IntegerDigits[n]]]; Select[Range[3, 10^5], DivisorSigma[1, rev[ # ]] == DivisorSigma[1, rev[ # - 1]] + DivisorSigma[1, rev[ # - 2]] &]
CROSSREFS
Sequence in context: A348280 A304150 A305505 * A305169 A316759 A334471
KEYWORD
base,nonn
AUTHOR
Joseph L. Pe, Apr 29 2002
STATUS
approved

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Last modified May 18 16:58 EDT 2024. Contains 372664 sequences. (Running on oeis4.)