A051152 -id:A051152 - cp's OEIS frontend

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A051153 (-1)-sigma super perfect numbers: (-1)sigma((-1)sigma(x))=2*x, where if x=Product p(i)^r(i) then (-1)sigma(x)=Product (-1+Sum p(i)^s(i), s(i)=1 to r(i)); (-1)sigma(1)=1.

Original entry on oeis.org

247, 988, 2808, 10440, 87696, 151200, 191052, 263520, 2630320, 3961980

Offset: 1

Yasutoshi Kohmoto

Factorizations: 13*19, 2^3*3^2*5*29, 2^4*3^3*7*29, 2^5*3^3*5^2*7, 2^2*3^3*29*61, 2^5*3^3*5*61, 2^7*3*5*11*19*29*1021

Cf. A049057, A049058, A049059, A049060, A034094, A051152.

A049060(n)={ local(i,resul,rmax,p) ; if(n==1, return(1) ) ; i=factor(n) ; rmax=matsize(i)[1] ; resul=1 ; for(r=1,rmax, p=0 ; for(j=1,i[r,2], p += i[r,1]^j ; ) ; resul *= p-1 ; ) ; return(resul) ; } isA051153(r)={ local(s,t) ; s=A049060(r) ; t=A049060(s) ; if( 2*r == t, return(1), return(0) ) ; } { for(n=1,30000000, if( isA051153(n), print(n,",") ) ; ) ; } \\ R. J. Mathar, Oct 12 2006

A049060(A049060(n))=2n. - R. J. Mathar, Oct 12 2006

Corrected and extended by R. J. Mathar, Oct 12 2006

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