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Search: id:A165739
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| A165739 |
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The number of palindromic numbers which are the product of a number and its reversal with 2n-1 digits |
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+0
1
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| 4, 3, 8, 13, 27, 49, 99, 180, 330, 567, 957, 1546, 2479, 3865
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Every palindromic numbers which is the product of a number and its reversal has an odd number of digits
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EXAMPLE
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a(1)=4 because there are 4 numbers matching the definition with one digit: 0*0=0; 1*1=1; 2*2=4; 3*3=9;
a(2)=3 because there are 3 numbers with three digits: 11*11=121; 12*21=252; 22*22=484;
a(3)=8 because there are 8 numbers with five digits: 101*101=10201; 111*111=12321; 121*121=14641; 102*201=20502; 112*211=23632; 122*221=26962; 202*202=40804; 212*212=44944;
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CROSSREFS
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Cf. A158642.
Sequence in context: A004125 A137924 A105185 this_sequence A137503 A108624 A108623
Adjacent sequences: A165736 A165737 A165738 this_sequence A165740 A165741 A165742
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KEYWORD
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nonn
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AUTHOR
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Floris P. van Doorn (florisvandoorn(AT)hotmail.com), Sep 25 2009
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