A069970 Numbers n such that sigma(reverse(n)) = sigma(reverse(n-1)) + sigma(reverse(n-2)).

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

Offset

1,1

Links

Table of n, a(n) for n=1..25.

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

Adjacent sequences: A069967 A069968 A069969 * A069971 A069972 A069973

Keyword

base,nonn

Author

Joseph L. Pe, Apr 29 2002

Status

approved