A325380 Numbers k in A228058 such that also A001065(k) is in A228058.

801, 1377, 1773, 2525, 3725, 4689, 4753, 6309, 6425, 7209, 7677, 8577, 8957, 9477, 11133, 11225, 11493, 11925, 12393, 12429, 12789, 13077, 15381, 15777, 18873, 19269, 19845, 20025, 20629, 21213, 24201, 26073, 26721, 28037, 28989, 29277, 29961, 30037, 30213, 31925, 32553, 33273, 34425, 34677, 36369, 36441, 38725, 39249, 40329

Offset

1,1

Comments

If any odd perfect number exists, then it must occur in this sequence.

Links

Antti Karttunen, Table of n, a(n) for n = 1..10000

Index entries for sequences where any odd perfect numbers must occur

Prog

(PARI)
A001065(n) = (sigma(n)-n);
isA228058(n) = if(!(n%2)||(omega(n)<2), 0, my(f=factor(n), y=0); for(i=1, #f~, if(1==(f[i, 2]%4), if((1==y)||(1!=(f[i, 1]%4)), return(0), y=1), if(f[i, 2]%2, return(0)))); (y));
k=0; n=0; while(k<100, n++; if(isA228058(n)&&isA228058(A001065(n)), k++; print1(n, ", ")));

Crossrefs

Cf. A001065, A228058, A325377.

Sequence in context: A107553 A357544 A031897 * A259949 A296962 A075005

Adjacent sequences: A325377 A325378 A325379 * A325381 A325382 A325383

Keyword

nonn

Author

Antti Karttunen, Apr 22 2019

Status

approved