id:A130686 - OEIS Search Results

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Absolute difference of final digits of two consecutive triangular numbers.

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1, 2, 3, 6, 5, 4, 7, 2, 1, 0, 1, 2, 7, 4, 5, 6, 3, 2, 1, 0, 1, 2, 3, 6, 5, 4, 7, 2, 1, 0, 1, 2, 7, 4, 5, 6, 3, 2, 1, 0, 1, 2, 3, 6, 5, 4, 7, 2, 1, 0, 1, 2, 7, 4, 5, 6, 3, 2, 1, 0, 1, 2, 3, 6, 5, 4, 7, 2, 1, 0, 1, 2, 7, 4, 5, 6, 3, 2, 1, 0, 1, 2, 3, 6, 5, 4, 7, 2, 1, 0, 1, 2, 7, 4, 5, 6, 3, 2, 1, 0, 1, 2, 3, 6, 5 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Periodic with period 20.`
	FORMULA	`a(n)=abs{ A010879[A000217(n+1)] - A010879[A000217(n)] }. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 15 2007` `a(n)=(1/950){-32(n mod 20)+63[(n+1) mod 20]+63[(n+2) mod 20]+63[(n+3) mod 20]+158[(n+4) mod 20]-32[(n+5) mod 20]-32[(n+6) mod 20]+158[(n+7) mod 20]-222[(n+8) mod 20]-32[(n+9) mod 20]-32[(n+10) mod 20]+63[(n+11) mod 20]+63[(n+12) mod 20]+253[(n+13) mod 20]-127[(n+14) mod 20]+63[(n+15) mod 20]+63[(n+16) mod 20]-127[(n+17) mod 20]-32[(n+18) mod 20]-32*[(n+19) mod 20]}, with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Oct 23 2008]`
	MAPLE	`A000217 := proc(n) n*(n+1)/2 ; end: A010879 := proc(n) n mod 10 ; end: A130686 := proc(n) abs(A010879(A000217(n+1))-A010879(A000217(n))) ; end: seq(A130686(n), n=0..80) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 15 2007`
	CROSSREFS	`Cf. A008954.` `Sequence in context: A011159 A091556 A072298 this_sequence A056023 A133259 A120067` `Adjacent sequences: A130683 A130684 A130685 this_sequence A130687 A130688 A130689`
	KEYWORD	`base,easy,nonn`
	AUTHOR	`Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Jun 30 2007`

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Last modified December 20 16:54 EST 2009. Contains 171081 sequences.

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