20047

Properties

Appears in sequences

• Sums of 7 distinct powers of 3.at n=36A038469
• Luhn primes: primes p such that p + (p reversed) is also a prime.at n=29A061783
• Integer part of log(n!)^(1 + log(1 + log(n))).at n=25A062443
• Sums of groups in A075635.at n=31A075636
• Expansion of 1/(1 - 8x + 17x^2).at n=6A106393
• Number of squares in an n X n grid of squares with diagonals.at n=26A111500
• Primes and their indices such that when their respective SOD's are both prime, the SOD of the index is the nextprime of the prime SOD.at n=30A117458
• Primes p such that (3^p - 3^((p + 1)/2) + 1)/7 is prime.at n=7A125743
• Running prime totals of prime factors (without multiplicity) of consecutive composite N.at n=42A140610
• Primes congruent to 46 mod 59.at n=36A142773
• Primes congruent to 39 mod 61.at n=35A142837
• Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 01000-11100-00111-00010 pattern in any orientation.at n=13A147334
• a(n) = 13*n^2 + 7*n + 1.at n=38A168240
• Values of y such that x^2 + y^2 = 17^n with x and y coprime and 0 < x < y.at n=6A230623
• Numbers n such that the Eisenstein integer ((1-ω)^n+1)/(2-ω) has prime norm, where ω = - 1/2 + sqrt(-3)/2.at n=18A239842
• Primes that can be generated by the concatenation in base 4, in ascending order, of two consecutive integers read in base 10.at n=16A287302
• The number of integers m in the range 0 < m < 10^n which are not divisible by any of their own digits (A038772).at n=4A327561
• Primes which, when added to their reversals, produce palindromic primes.at n=6A342681
• Primes of the form A321513(k) + 1 for some k > 0.at n=30A352966
• Value of A121805(k) for k = A367358(n).at n=23A367359