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A047235 Numbers that are congruent to {2, 4} mod 6. +0
10
2, 4, 8, 10, 14, 16, 20, 22, 26, 28, 32, 34, 38, 40, 44, 46, 50, 52, 56, 58, 62, 64, 68, 70, 74, 76, 80, 82, 86, 88, 92, 94, 98, 100, 104, 106, 110, 112, 116, 118, 122, 124, 128, 130, 134, 136, 140, 142, 146, 148, 152, 154, 158, 160, 164, 166, 170, 172, 176, 178, 182, 184, 188, 190, 194, 196, 200, 202, 206 (list; graph; listen)
OFFSET

1,1

COMMENT

Apart from initial term(s), dimension of the space of weight 2n cuspidal newforms for Gamma_0( 19 ).

Complement of A047273; A093719(a(n)) = 0. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 01 2008]

Apart from initial terms, a(n)=6*n-a(n-1), (with a(1)=4) Example: n=2, a(2)=6*2-4=8; n=3, a(3)=6*3-8=10; n=4, a(4)=6*4-10=14 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 17 2009]

LINKS

C. Lai, A note on potentially K_4-e graphical sequences

William A. Stein, Dimensions of the spaces S_k^{new}(Gamma_0(N))

William A. Stein, The modular forms database

FORMULA

n such that phi(3n)=phi(2n) - Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 06 2003

G.f.: 2x(1+x+x^2)/((1+x)(1-x)^2). a(n) = 3n -3/2 -(-1)^n/2. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 22 2008]

PROGRAM

(MAGMA) [ n eq 1 select 2 else Self(n-1)+2*(1+n mod 2): n in [1..70] ]; [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Dec 13 2008]

CROSSREFS

Equals 2*A001651(n).

Sequence in context: A030232 A102024 A104197 this_sequence A087505 A086801 A154115

Adjacent sequences: A047232 A047233 A047234 this_sequence A047236 A047237 A047238

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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Last modified November 23 17:09 EST 2009. Contains 167438 sequences.


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