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A098897
Palindromic deficient numbers.
2
1, 2, 3, 4, 5, 7, 8, 9, 11, 22, 33, 44, 55, 77, 99, 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 202, 212, 232, 242, 262, 292, 303, 313, 323, 333, 343, 353, 363, 373, 383, 393, 404, 424, 434, 454, 484, 494, 505, 515, 525, 535, 545, 555, 565, 575, 585, 595
OFFSET
1,2
LINKS
EXAMPLE
a(10)=22 because 22 is the tenth deficient number which is palindromic also.
MATHEMATICA
Select[Range@ 900, And[DivisorSigma[1, #] < 2 #, PalindromeQ@ #] &] (* Michael De Vlieger, Nov 08 2017 *)
nxtPal[n_]:=With[{c=Join[{2}, Flatten[Table[{10 10^d, 11 10^d}, {d, 0, 10}]]]}, SelectFirst[n+c, PalindromeQ]]; Join[{1, 2, 3, 4, 5, 7, 8}, Select[ NestList[ nxtPal[#]&, 9, 100], DivisorSigma[1, #]<2#&]] (* Harvey P. Dale, Nov 14 2024 *)
PROG
(PARI) isok(n) = (sigma(n) < 2*n) && (d=digits(n)) && (Vecrev(d) == d); \\ Michel Marcus, Nov 08 2017
CROSSREFS
Intersection of A002113 and A005100.
Sequence in context: A080664 A230762 A098776 * A265641 A192140 A084092
KEYWORD
easy,nonn,base,changed
AUTHOR
Shyam Sunder Gupta, Oct 14 2004
STATUS
approved