121801

Appears in sequences

• a(n) = (10*n + 9)^2.at n=34A017378
• a(n) = (11*n + 8)^2.at n=31A017486
• a(n) = (12*n + 1)^2.at n=29A017534
• a(n) = prime^2 and digits of prime do not appear in a(n).at n=15A030088
• Numbers k such that k + 1 has one more divisor than k.at n=34A055927
• Numbers n such that sigma(d(n^3))==d(sigma(n^2)), where d(n) is the number of divisors of n.at n=25A063797
• Composite numbers not divisible by 5 which in base 5 contain their largest proper factor as a substring.at n=22A063889
• Squares k such that k + pi(k) is a prime.at n=34A073946
• Number of ways to partition 2*n into distinct positive integers not greater than n.at n=43A079122
• Square of primes of the form 4k+1 (A002144).at n=32A080109
• Numbers m such that Sum_{p prime|m} p^r(p) = m, where r(p) is the least positive primitive root of p (A001918).at n=35A101051
• Squares of the form prime(k)*prime(k+1) + 2*prime(k+1).at n=20A108604
• Squares of the form 2*p+3 that are squares of primes.at n=32A110588
• Prime powers p^k with even exponents k > 0 such that (1 + p^k)/2 is prime.at n=21A192618
• Number of n X 4 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 0 1 1 vertically.at n=11A208009
• Lucky numbers that are prime powers.at n=31A225322
• Perfect powers equal to the sum of 6 factorial numbers.at n=37A227647
• Square numbers in A070552.at n=15A263951
• Number of (n+1)X(3+1) arrays of permutations of 0..n*4+3 with each element having directed index change -1,0 0,2 -1,-2 or 1,0.at n=9A264515
• Odd squares not of the form p + 2^k with p prime.at n=4A276567