A086073 - OEIS

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A086073

Number of 2's in decimal expansion of triangular number n(n+1)/2.

0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1, 1, 2, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,50`
	EXAMPLE	`tri(49)=1225, so a(49)=2 and tri(651)=212226, so a(651)=4.`
	CROSSREFS	`Cf. 0's A086071, 1's A086072, 3's A086074, 4's A086075, 5's A086076, 6's A086077, 7's A086078, 8's A086079, 9's A086080.` `Sequence in context: A139037 A108511 A196272 * A053622 A016408 A106822` `Adjacent sequences: A086070 A086071 A086072 * A086074 A086075 A086076`
	KEYWORD	`base,nonn`
	AUTHOR	`Jason Earls (zevi_35711(AT)yahoo.com), Jul 08 2003`

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Last modified February 17 11:35 EST 2012. Contains 206011 sequences.