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A028980 Numbers whose sum of divisors is palindromic. 7
1, 2, 3, 4, 5, 7, 43, 81, 96, 98, 130, 146, 162, 166, 201, 205, 208, 211, 221, 241, 244, 251, 271, 274, 281, 300, 314, 325, 333, 365, 388, 422, 433, 438, 443, 463, 489, 519, 559, 633, 685, 793, 803, 827, 857, 877, 887, 1376, 1419, 1505, 1548 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
Patrick De Geest, World!Of Numbers
MAPLE
isA028980 := proc(n)
isA002113(numtheory[sigma](n)) ;
end proc:
for n from 1 to 2000 do
if isA028980(n) then
printf("%d, ", n) ;
end if;
end do: # R. J. Mathar, Sep 09 2015
MATHEMATICA
Select[Range[1550], Reverse[x=IntegerDigits[DivisorSigma[1, #]]]==x&] (* Jayanta Basu, Jun 05 2013 *)
Select[Range[1600], PalindromeQ[DivisorSigma[1, #]]&] (* Harvey P. Dale, Jul 20 2021 *)
CROSSREFS
Sequence in context: A276522 A135709 A263043 * A183108 A096841 A029963
KEYWORD
nonn,base
AUTHOR
STATUS
approved

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Last modified March 19 06:17 EDT 2024. Contains 370952 sequences. (Running on oeis4.)