21943

Properties

Appears in sequences

• a(n) = n^3 - floor( n/3 ).at n=28A002901
• Smallest prime q such that (p^q+1)/(p+1) is a prime, where p = prime(n).at n=15A065507
• Numbers n such that [A070080(n), A070081(n), A070082(n)] is an obtuse isosceles integer triangle with prime side lengths.at n=29A070135
• Largest prime < n^3.at n=26A077037
• Least k such that (n^k+1)/(n+1) is prime, or 0 if no such prime exists.at n=51A084742
• Primes p having exactly one partition into distinct divisors of p+1.at n=38A085499
• Primes p = p_(n+1) such that p_n + p_(n+2) = 2*p_(n+1) + 12.at n=19A095673
• Primes of the form Sum_{k=1..n} phi(prime(k)).at n=16A101302
• Prime Friedman numbers.at n=16A112419
• Least number k > 0 such that ((2n-1)^k + 1)/(2n) is prime, or 0 if no such prime exists.at n=25A126659
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, 0), (0, 1, -1), (1, -1, 0), (1, 1, 1)}.at n=8A149693
• Partial sums of A006567.at n=40A172463
• Primes of the form 8*k^2 + 6*k - 1 for positive k.at n=28A187677
• Primes of the form 8n^3-9.at n=3A200959
• Primes of the form 7n^2 - 9.at n=12A201854
• 2*n^3 - 313*n^2 + 6823*n - 13633.at n=8A218456
• Lesser of consecutive primes whose average is a perfect power.at n=24A242380
• Lesser of consecutive primes whose average is a perfect cube.at n=4A242382
• In the '3x+1' problem, primes which as starting values set new records for number of steps to reach 1, where a step means either 'divide by two' or 'triple plus one and then divide by two'.at n=23A244638
• a(0) = 2; for n>0, a(n) = smallest prime p such that p > a(n-1) and p is congruent to n modulo prime(n).at n=42A261192