79523
domain: N
Appears in sequences
- Numbers that are the product of a pair of twin primes.at n=18A037074
- Product of twin primes of form (4*k+1,4*k+3), k>0.at n=9A071697
- Numbers n such that n+1 and phi(n)+1 are both perfect squares.at n=35A089952
- Numbers k such that k+1 and sigma(k)+1 are both perfect squares.at n=23A089954
- Number of partitions of 2n in which each odd part has even multiplicity and each even part has odd multiplicity.at n=33A100847
- Numbers k equal prime(n)*prime(n+1) such that k+1 is a square and k-1 is even semiprime.at n=7A107423
- Numbers k such that lcm(1,2,3,...,k)/17 equals the denominator of the k-th harmonic number H(k).at n=33A112820
- Numbers that are one less than a square and have exactly 4 divisors.at n=19A134020
- Members of A159053 which are not multiples of 3.at n=9A159054
- Semiprimes which are sub-perfect powers.at n=28A189045
- Numbers k that form a primitive Pythagorean triple with k' and sqrt(k^2 + k'^2), where k' is the arithmetic derivative of k.at n=21A210503
- Nonprime n not divisible by 2 or 3 such that Fibonacci(n-1) is congruent to (1 - Legendre(n,5))/2 modulo n.at n=29A220292
- Least number k such that n divides gcd(sigma(k), phi(k)) (A009223).at n=46A222713
- Smallest i such that prime(n) divides gcd(sigma(i), phi(i)) (cf. A009223).at n=14A222714
- Increasing a(n)is the smallest number of the form p^a*q^b, where a,b are positive integers and p < q are odd primes such that max( p^a, q^b)/min( p^a, q^b) <= 1 + 2/prime(n).at n=32A229108
- Numbers that are both a sum and a product of two or more consecutive primes.at n=30A254859
- Quasi-Carmichael numbers to exactly three bases.at n=24A257753
- Semiprimes whose prime factors are of equal binary length and which differ from each other in one bit position only.at n=34A261073
- Semiprimes p*q for which p and q are successive primes and their binary representations differ from each other in one bit position only.at n=16A261080
- Numbers n which are neither a prime nor a square of a prime such that there is no d, 2<=d<=n/2, which divides binomial(n-d-1,d-1) and is not coprime to n.at n=27A269135