id:A055258 - OEIS Search Results

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Sums of two powers of 7.

+0
2

2, 8, 14, 50, 56, 98, 344, 350, 392, 686, 2402, 2408, 2450, 2744, 4802, 16808, 16814, 16856, 17150, 19208, 33614, 117650, 117656, 117698, 117992, 120050, 134456, 235298, 823544, 823550, 823592, 823886, 825944, 840350, 941192, 1647086 (list; table; graph; listen)

	OFFSET	`0,1`
	FORMULA	`a(n) = 7^(n-trinv(n))+7^trinv(n), where trinv(n) = floor((1+sqrt(1+8*n))/2) = A002262(n) and n-trinv(n) = A003056(n)` `Regarded as a triangle T(n, k)=7^n+7^k, so as a sequence a(n) =7^A002262(n)+7^A003056(n).`
	EXAMPLE	`a(4) = 56 = 7^2+7^1`
	CROSSREFS	`Cf. A052216.` `Equals 2*A073218.` `Sequence in context: A039660 A119752 A111001 this_sequence A054981 A059449 A065907` `Adjacent sequences: A055255 A055256 A055257 this_sequence A055259 A055260 A055261`
	KEYWORD	`base,easy,nonn,tabl`
	AUTHOR	`Henry Bottomley (se16(AT)btinternet.com), Jun 22 2000`

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Last modified August 29 17:54 EDT 2008. Contains 143238 sequences.

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