21783

Appears in sequences

• Numbers k such that k and 4*k are anagrams.at n=15A023088
• a(n) = (d(n)-r(n))/2, where d = A026049 and r is the periodic sequence with fundamental period (1,0,0,1).at n=46A026050
• a(n) = n-th prime number * n-th lucky number.at n=32A032601
• Values of A038005 ending in 3.at n=28A038013
• Least K such that K*p(n)#-1 is the first of twin primes and 2*(K*p(n)#-1)+1 is prime, so K*p(n)#-1 is the first of twin primes and a Sophie Germain prime.at n=47A117848
• a(n) = 20*n^2 + 3.at n=32A167573
• Number of ways to write n as an ordered sum of 6 prime powers (including 1).at n=20A341135
• G.f. A(x) = Sum_{n>=0} a(n)*x^n satisfies: [Sum_{n>=0} x^n/(1 - x^(n+1))]^3 = Sum_{n>=0} a(n)*x^n/(1 - x^(n+1))^3.at n=43A341374
• Numbers k such that k - A067666(k) is a square.at n=39A386304