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.

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A274118 (1+e)-sigma betrothed numbers.

Original entry on oeis.org

108, 140, 195, 1050, 1925, 8892, 16587, 312620, 549219, 587460, 1057595, 1279950, 2576945, 5088650, 6446325, 7460004, 7875450, 10925915, 13922100, 16381925, 22559060, 26502315, 29864120, 30809415, 31213899, 41137620, 84854315, 89446860, 102019644, 114859884
Offset: 1

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Author

Paolo P. Lava, Jun 10 2016

Keywords

Comments

Members of a pair (m,n) such that (1+e)-sigma(m)=(1+e)-sigma(n)=m+n+1, where (1+e)-sigma = A051378.
So far, 108 is the only fixed point of the transform n -> (1+e)sigma(n)-n-1.

Examples

			(1+e)-sigma(140) - 140 - 1 = 336 - 140 - 1 = 195 and (1+e)-sigma(195) - 195 - 1 = 336 - 195 - 1 = 140.
		

Crossrefs

Programs

  • Maple
    with(numtheory): T:=proc(n) local a,d,p,e,s,sp; a:=1;
    for d in ifactors(n)[2] do p:=op(1,d); e:= op(2,d); sp:=1;
    for s in divisors(e) do sp:=sp+p^s; od: a:=a*sp; od: a; end:
    P:=proc(q) local n,x,y; for n from 2 to q do x:=T(n)-n-1; y:=T(x)-x-1;
    if n=y then print(n); fi; od; end: P(10^10);
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