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A007604 Sequence formed from rows of triangle A046936.
(Formerly M0567)
4
1, 2, 3, 4, 6, 9, 12, 16, 22, 31, 40, 52, 68, 90, 121, 152, 192, 244, 312, 402, 523, 644, 796, 988, 1232, 1544, 1946, 2469, 2992, 3636, 4432, 5420, 6652, 8196, 10142, 12611, 15080, 18072, 21708, 26140, 31560, 38212, 46408, 56550, 69161, 81772, 96852 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

COMMENTS

A003056(n) gives the number of odd terms in the first n terms of this sequence. Modulo 2, this sequence becomes A023531. - T. D. Noe, Jul 24 2007

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

FORMULA

a(n)=a(n-1)+a(n-1- number of odd terms so far).

MATHEMATICA

a[n_Integer] := a[n] = Block[{c, k}, c = 0; k = 1; While[k < n, If[ OddQ[ a[k] ], c++ ]; k++ ]; Return[a[n - 1] + a[n - 1 - c] ] ]; a[1] = 1; a[2] = 2; Table[ a[n], {n, 0, 60} ]

CROSSREFS

Cf. A006336

Sequence in context: A069907 A001935 A083365 * A013950 A018550 A035952

Adjacent sequences:  A007601 A007602 A007603 * A007605 A007606 A007607

KEYWORD

nonn,nice,easy

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com), Robert G. Wilson v (rgwv(AT)rgwv.com)

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Last modified February 16 23:43 EST 2012. Contains 205978 sequences.