Back Vollkommene Zahl#Pseudovollkommene Zahlen German Ημιτέλειος αριθμός Greek Duonperfekta nombro Esperanto Número semiperfecto Spanish Puolitäydellinen luku Finnish Nombre semi-parfait French מספר דמוי משוכלל HE Áltökéletes számok Hungarian Numero semiperfetto Italian 擬似完全数 Japanese
 Demonstration, with Cuisenaire rods, of the perfection of the number 6. | |
| Total no. of terms | infinity |
|---|---|
| First terms | 6, 12, 18, 20, 24, 28, 30 |
| OEIS index |
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In number theory, a semiperfect number or pseudoperfect number is a natural number n that is equal to the sum of all or some of its proper divisors. A semiperfect number that is equal to the sum of all its proper divisors is a perfect number.
The first few semiperfect numbers are: 6, 12, 18, 20, 24, 28, 30, 36, 40, ... (sequence A005835 in the OEIS)