20026

Appears in sequences

• Pseudoprimes to base 35.at n=39A020163
• Sum of squares of first n positive integers congruent to 1 mod 3.at n=18A024215
• Even 9-gonal (or enneagonal) numbers.at n=38A028992
• Numbers k such that usigma(k) = phi(k)*omega(k), where omega(k) is the number of distinct prime divisors of k.at n=14A063795
• Numbers n such that the arithmetic, geometric and harmonic means of phi(n) and sigma(n) are all integers.at n=13A065146
• Numbers k such that sigma(k) = bigomega(k) * phi(k).at n=9A067238
• Numbers k such that sigma(k) = 4*phi(k).at n=11A068390
• Numbers k such that sigma(k) = phi(k*bigomega(k)).at n=8A068400
• Numbers k such that sigma(k) = phi(k)*omega(k).at n=5A073567
• Squarefree balanced numbers (i.e., squarefree members of A020492).at n=34A078557
• Numbers which are sums of two and also sums of three positive cubes.at n=36A085336
• Numbers which are sums of two, three and four cubes.at n=24A085337
• Numbers which are sums of two, three, four and also sums of five cubes.at n=23A085338
• 45-gonal numbers: n*(43*n-41)/2.at n=30A098924
• Numbers which are the sum of two positive cubes and divisible by 17.at n=18A099178
• Numbers which are the sum of two positive cubes and divisible by 31.at n=32A102658
• Enneagonal numbers for which the product of the digits is also an enneagonal number.at n=23A117052
• Numbers such that Sigma(m)*UnitarySigma(m)= k*UnitaryPhi(m)^2, for some integer k.at n=40A122839
• Numbers m such that UnitarySigma(m)^2 = k*Sigma(m)*UnitaryPhi(m), for some integer k.at n=40A123041
• Partial sums of A005109.at n=24A172167