A351574 Terms of A228058 missing from A347874.

117, 245, 333, 425, 549, 605, 637, 657, 725, 833, 845, 873, 981, 1025, 1053, 1325, 1413, 1421, 1445, 1629, 1737, 1805, 1813, 2009, 2057, 2061, 2169, 2225, 2493, 2525, 2597, 2645, 2817, 2825, 2873, 2925, 2989, 2997, 3033, 3141, 3357, 3425, 3509, 3573, 3577, 3681, 3725, 3789, 3897, 4113, 4205, 4325, 4361, 4693, 4753

Offset: 1

Author

Antti Karttunen, Feb 23 2022

Keywords

• nonn
• changed

Comments

Numbers that satisfy Euler's criterion for the odd perfect numbers (A228058), but do not satisfy the criterion specified in A347874.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to sigma(n)

Crossrefs

Setwise difference A228058 \ A347874, also setwise difference A228058 \ A386429.

Cf. A000203, A003415.

Programs

PARI

A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A342926(n) = (A003415(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));
isA347874(n) = ((n%2)&&!isprime(n)&&!(A342926(n)%2)&&!(A342926(2*n)%3));
isA351574(n) = (isA228058(n) && !isA347874(n));