[seqfan] Re: A104149 More terms

[Maximilian Hasler]

there's also the symmetric version:

A076530		 Numbers n such that sigma(n) = sigma(n+1) - sigma(n-1).		+20
1
2, 3, 23, 1967, 3263, 5015, 60455, 1016507, 4420163, 12055511,
14365607, 25726727, 27896423, 66562307, 72764735, 98734967, 175186655,
224868311, 253694927, 288657203, 386668343, 421575407, 504737747,
630645455, 1493547999

M.

On Thu, Aug 19, 2010 at 10:36 AM, Richard Mathar
<mathar at strw.leidenuniv.nl> wrote:
>
> http://list.seqfan.eu/pipermail/seqfan/2010-August/005718.html
>
> This is easy with a little bit of cheating:
>
> %I A104149
> %S A104149 1,2,22,1966,3262,5014,60454,1016506,4420162,12055510,14365606,25726726,
> %T A104149 27896422,66562306,72764734,98734966,175186654,224868310,253694926,288657202,
> %U A104149 386668342,421575406,504737746,630645454
> %N A104149 Numbers n such that sigma(n+2) = sigma(n+1) + sigma(n).
> %F A104149 a(n) = A065900(n)-2 . [R. J. Mathar, Aug 19 2010]
> %e A104149 sigma(22) = 1+2+11+22 = 36
> %e A104149 sigma(23) = 1+23 = 24
> %e A104149 sigma(24) = 1+2+3+4+6+8+12+24 = 60
> %e A104149 sigma(24)  = sigma(23) + sigma(22)
> %K A104149 more,nonn,new
> %O A104149 1,2
> %A A104149 Neven Juric (neven.juric(AT)apis-it.hr), Aug 16, 2010
> %E A104149 More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 19 2010
>
>
>
>
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