21520

Appears in sequences

• Numbers k such that 153*2^k-1 is prime.at n=38A050618
• Intrinsic 10-palindromes: n is an intrinsic k-palindrome if it is a k-digit palindrome in some base.at n=23A060947
• a(n) = 2*a(n-1) + 6*a(n-2), a(0) = 0, a(1) = 1.at n=9A083099
• a(n) = A000695(A014486(n)).at n=20A083931
• Pseudo-random numbers: Davenport's generator for 32-bit integers.at n=1A084277
• Let b(0)=1; b(1)=1; b(n+2) = (Pi^2/6 + 6/Pi^2)*b(n+1) - b(n). a(n) = floor(b(n)).at n=20A093607
• In the "3x+1" problem, let 0 denote a halving step and 1 denote an x->3x+1 step. Then a(n) is obtained by writing the sequence of steps needed to reach 1 from 2n+1 and reading it as a decimal number.at n=11A125710
• Even integers k such that lambda(sum of even divisors of k) = sum of odd divisors of k.at n=29A293356
• a(n) is the least number that reaches 1 after n iterations of the infinitary totient function A064380.at n=33A362025