cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A291769 Restricted growth sequence transform of A292249; filter combining multiplicative order of 2 mod 2n+1 & prime signature of 2n+1 (A002326 & A278223).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 18, 32, 33, 34, 35, 36, 37, 38, 39, 40, 25, 41, 12, 18, 17, 42, 43, 44, 45, 46, 47, 48, 19, 42, 15, 49, 22, 50, 51, 27, 52, 53, 54, 55, 28, 56, 57, 58, 59, 60, 41, 61, 62, 63, 64, 27, 26, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 60, 42
Offset: 0

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Author

Antti Karttunen, Oct 02 2017

Keywords

Comments

Also restricted growth sequence transform of the odd bisection of A286573.

Crossrefs

Cf. A291766, A292267 for related filters.

Programs

  • PARI
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    A002326(n) = if(n<0, 0, znorder(Mod(2, 2*n+1))); \\ This function from Michael Somos, Mar 31 2005
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ This function from Charles R Greathouse IV, Aug 17 2011
    A292249(n) = (1/2)*(2 + ((A002326(n)+A046523(n+n+1))^2) - A002326(n) - 3*A046523(n+n+1));
    write_to_bfile(0,rgs_transform(vector(32769,n,A292249(n-1))),"b291769_upto32768.txt");