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A131229 Numbers congruent to {1,7} mod 10. +0
4
1, 7, 11, 17, 21, 27, 31, 37, 41, 47, 51, 57, 61, 67, 71, 77, 81, 87, 91, 97, 101, 107, 111, 117, 121, 127, 131, 137, 141, 147, 151, 157, 161, 167, 171, 177, 181, 187 (list; graph; listen)
OFFSET

1,2

FORMULA

Row sums of triangle A131228.

a(n)=-3+Sum_{k=0..n}{5-(-1)^k} - Paolo P. Lava (ppl(AT)spl.at), Nov 05 2007

a(n) = a(n-2)+10 = 5*n+((-1)^n-7)/2. O.g.f.: x*(1+6*x+3*x^2)/((-1+x)^2*(1+x)) . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 17 2008

EXAMPLE

11 = a(3) = 1 mod 10.

11 = a(3) = row 4 sums, triangle A131228: (1 + 3 + 7).

CROSSREFS

Cf. A128174, A051340, A131228.

Sequence in context: A019365 A078497 A063639 this_sequence A092737 A072669 A108101

Adjacent sequences: A131226 A131227 A131228 this_sequence A131230 A131231 A131232

KEYWORD

nonn

AUTHOR

Gary W. Adamson (qntmpkt(AT)yahoo.com), Jun 20 2007

EXTENSIONS

More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 17 2008

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Last modified December 2 15:58 EST 2008. Contains 150992 sequences.


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