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Search: id:A094534
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| A094534 |
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3n(n-1)+1 ends in n (similar to the automorphic or curious numbers, 3n(n-1)+1 is the n-th hexagonal number rather than the n-th square; see A003226). |
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+0
1
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| 1, 7, 17, 51, 67, 167, 251, 417, 501, 667, 751, 917, 1251, 1667, 5001, 5417, 6251, 6667, 10417, 16667, 50001, 56251, 60417, 66667, 166667, 260417, 406251, 500001, 666667, 760417, 906251, 1406251, 1666667, 5000001, 5260417, 6406251, 6666667, 16666667
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Given any number in the sequence, if you remove one or more digits from the beginning you always get another number in the sequence. This makes it easy to find higher terms -- just take an existing term and try adding a digit (with perhaps additional 0's) at the beginning. For example, to 6251 prepend 5 to get a 5-digit term, or 40 or 90 to get a 6-digit term.
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LINKS
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Robert Munafo, Sequence A094534, Centered Hexamorphic, or Automorphic Hexagonal, Numbers
Cliff Pickover, Centered Hexamorphic Numbers.
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FORMULA
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10^(d-1) <= n < 10^d; 3n(n-1)+1 == n mod 10^d
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EXAMPLE
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417 is in the sequence because if n=417, 3n(n-1)+1=520417, which ends in 417.
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CROSSREFS
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Cf. A003215, A003226.
Sequence in context: A018672 A045821 A115914 this_sequence A081632 A106010 A136192
Adjacent sequences: A094531 A094532 A094533 this_sequence A094535 A094536 A094537
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KEYWORD
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base,easy,nonn
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AUTHOR
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Robert Munafo (mrob(AT)mrob.com), May 07 2004
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