20003

Appears in sequences

• n written in fractional base 4/2.at n=35A024630
• Numbers n with property that n is a substring of its base 5 representation.at n=13A038105
• Numbers k such that sigma(phi(sigma(k))) = phi(sigma(phi(k))).at n=17A067160
• List the positions of all digits '1' in the sequence. This is the lexicographically earliest increasing sequence with this property.at n=41A098645
• Numbers k such that 11k = 6j^2 + 6j + 1.at n=34A106388
• Composite solutions of the form 4k+3 of the equation (*): sigma(phi(sigma(x)))=phi(sigma(phi(x))).at n=3A112017
• a(n) is the least semiprime > a(n-1) whose digits do not appear in a(n-1).at n=27A131220
• a(n) = 2*10^n + 3.at n=4A173041
• Numbers k such that neighboring digits of k^22 are distinct.at n=13A318763
• Lexicographically earliest sequence of nonnegative terms forming a clockwise square spiral when nothing else is read except the parity of the digits or the parity of the terms (see the Comments section).at n=56A341903
• Lexicographically earliest sequence of distinct positive terms not ending in 0 such that the Levenshtein distance (Ld) between a(n) and a(n+1) is equal to the last digit of a(n).at n=46A367810