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Search: id:A046181
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A046181 Indices of octagonal numbers which are also triangular. +0
3
1, 3, 63, 261, 6141, 25543, 601723, 2502921, 58962681, 245260683, 5777740983, 24033043981, 566159653621, 2354993049423, 55477868313843, 230765285799441, 5436264935102961, 22612643015295763 (list; graph; listen)
OFFSET

1,2

LINKS

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

FORMULA

For n odd, a(n+2)=98*a(n+1)-a(n)-32; for n even, a(n+1)=49*a(n)-16+10*(24*a(n)^2-16*a(n)+1)^0.5 - Richard Choulet (richardchoulet(AT)yahoo.fr), Oct 03 2007, Oct 09 2007

CROSSREFS

Cf. A046182, A046183.

Cf. A046182 A046183.

Sequence in context: A087886 A123754 A048354 this_sequence A120053 A139293 A133275

Adjacent sequences: A046178 A046179 A046180 this_sequence A046182 A046183 A046184

KEYWORD

nonn

AUTHOR

Eric Weisstein (eric(AT)weisstein.com)

EXTENSIONS

More terms from Richard Choulet (richardchoulet(AT)yahoo.fr), Oct 03 2007

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Last modified July 25 07:41 EDT 2008. Contains 142293 sequences.


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