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.

A291966 Numerators of fractions with the anomalous cancellation property, corresponding to denominators listed in A291965.

Original entry on oeis.org

16, 26, 19, 49, 22, 33, 34, 44, 55, 64, 66, 77, 138, 148, 88, 95, 96, 97, 39, 49, 99, 101, 103, 104, 124, 121, 33, 34, 44, 55, 65, 66, 106, 67, 77, 88, 97, 98, 99, 149, 101, 102, 206, 13, 163, 132, 83, 134, 136, 44, 138, 55, 66, 146, 77, 88, 195, 49, 197, 79, 99, 199, 101, 203, 102, 244, 145, 143, 55, 66, 116, 186, 67, 77, 88, 98, 99, 101
Offset: 1

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Author

M. F. Hasler, Sep 06 2017

Keywords

Comments

See A291965 for more details, comments and references.

Examples

			The two-digit examples 16/64, 26/65, 19/95, 49/98 are well known.
The earliest three-digit terms of A291965 correspond to 34/136 = 4/16, 64/160 = 4/10, 138/184 = 3/4, ...
		

Crossrefs

Programs

  • PARI
    /* Note: a(n) = A291966(A291965(n))! This function does not yield the n-th term, but the numerator corresponding to denominator N in A291965; if N is not in A291965, it yields zero. */ A291966(n, dn=digits(n), Dn=Set(dn))={local(Cd, sc(x)=select(t->setsearch(Cd, t), x), rd(x)=local(S=0); fromdigits(select(d->!(setsearch(Cd, d)&&!bittest(S, d)&&S+=1<1 && #(Cd=setintersect(Set(dd=digits(d)), Dn)) && gcd(n, d)%10 ||next; rd(dd) || next; my(n1=rd(dn), d1=rd(dd), nd=digits(n1)); Cd=setintersect(Set(dd=digits(d1)), Set(nd)); if(#Cd, d*rd(nd)==n*rd(dd) && rd(dd), d*n1 == n*d1) && return(d))}
    /* To print this sequence: */ for(N=10,500,A291966(N)&&print1(A291966(N)","))