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A130686 Absolute difference of final digits of two consecutive triangular numbers. +0
1
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

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 July 24 12:00 EDT 2008. Contains 142294 sequences.


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