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A084831 Numbers n such that sum of odd divisors and sum of even divisors are both palindromic. 2
1, 2, 3, 4, 5, 6, 7, 43, 81, 86, 162, 201, 205, 211, 221, 241, 251, 271, 281, 325, 333, 344, 365, 422, 433, 443, 463, 482, 489, 519, 559, 633, 650, 685, 730, 793, 803, 827, 857, 866, 877, 886, 887, 1419, 1505, 1841, 2021, 2111, 2221, 2305, 2441, 2551, 2561, 2611 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Primes of form 2*10^n + R(n) (A056700) and 2/9*(-1+10^n)-1 (A084832) are members.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

a(11)=162 because sum of even divisors is 242 and sum of odd divisors is 121.

MATHEMATICA

sodQ[n_]:=Module[{dn=Divisors[n], o, e}, o=IntegerDigits[Total[Select[ dn, OddQ]]]; e=IntegerDigits[Total[Select[dn, EvenQ]]]; o== Reverse[o] && e==Reverse[e]]; Select[Range[3000], sodQ] (* Harvey P. Dale, Feb 27 2013 *)

CROSSREFS

Cf. A000593, A056700, A084832.

Sequence in context: A024645 A004847 A024646 * A037406 A237344 A024647

Adjacent sequences:  A084828 A084829 A084830 * A084832 A084833 A084834

KEYWORD

base,nonn

AUTHOR

Jason Earls, Jun 05 2003

STATUS

approved

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Last modified May 23 19:07 EDT 2019. Contains 323528 sequences. (Running on oeis4.)