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A098534 Mod 3 analog of Stern's diatomic series. 1
0, 1, 1, 2, 3, 2, 2, 4, 3, 4, 7, 5, 6, 5, 5, 4, 6, 4, 4, 8, 6, 8, 8, 7, 6, 10, 7, 8, 15, 11, 14, 10, 12, 10, 13, 11, 12, 11, 11, 10, 12, 10, 10, 11, 9, 8, 14, 10, 12, 10, 10, 8, 12, 8, 8, 16, 12, 16, 13, 14, 12, 17, 14, 16, 18, 16, 16, 17, 15, 14, 17, 13, 12, 22, 16, 20, 18, 17, 14, 22 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Essentially diagonal sums of Pascal's triangle modulo 3.

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..10000

FORMULA

a(n) = Sum_{k=0..floor((n-1)/2)} mod(binomial(n-k-1, k), 3).

MATHEMATICA

Table[Sum[Mod[Binomial[n - k - 1, k], 3], {k, 0, Floor[(n - 1)/2]}], {n, 0, 100}] (* G. C. Greubel, Jan 17 2018 *)

PROG

(PARI) for(n=0, 100, print1(sum(k=0, floor((n-1)/2), lift(Mod(binomial(n-k-1, k), 3))), ", ")) \\ G. C. Greubel, Jan 17 2018

(MAGMA) [0] cat [(&+[Binomial(n-k-1, k) mod 3: k in [0..Floor((n-1)/2)]]): n in [1..100]]; // G. C. Greubel, Jan 17 2018

CROSSREFS

Cf. A002487, A051638.

Sequence in context: A193827 A131340 A175470 * A317638 A002307 A287707

Adjacent sequences:  A098531 A098532 A098533 * A098535 A098536 A098537

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Sep 13 2004

STATUS

approved

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Last modified November 17 16:08 EST 2019. Contains 329241 sequences. (Running on oeis4.)