20197

Appears in sequences

• Numbers that are the sum of 7 nonzero 8th powers.at n=23A003385
• Numbers that are the sum of 4 positive 9th powers.at n=6A003393
• Numbers that are the sum of at most 4 positive 9th powers.at n=21A004888
• Numbers that are the sum of at most 5 positive 9th powers.at n=28A004889
• Numbers that are the sum of at most 6 positive 9th powers.at n=36A004890
• Pseudoprimes to base 7.at n=28A005938
• Strong pseudoprimes to base 7.at n=8A020233
• Strong pseudoprimes to base 49.at n=10A020275
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 82 ones.at n=24A031850
• Numbers n such that 91*2^n-1 is prime.at n=29A050571
• Numbers with sum of digits = 19, divisible by 19 and containing the string "19".at n=4A121669
• G.f.: 1/[(1-2x)(1+2x+3x^2)].at n=16A122508
• a(n) = 2+2^n+3^n.at n=9A173657
• Centered 36-gonal numbers.at n=33A195316
• Number of partitions p of n such that the number of parts is not a part and max(p) - min(p) is a part.at n=47A241383
• Euler pseudoprimes to base 7: composite integers such that abs(7^((n - 1)/2)) == 1 mod n.at n=19A262054
• Expansion of Product_{k>=1} (1 + x^k)^(sigma_9(k)).at n=3A301553
• Sum of the second largest parts in the partitions of n into 7 parts.at n=39A308932
• Numbers k such that k and k+2 are both A000120-perfect numbers (A175522).at n=24A360639
• a(n) = Sum_{k=0..n} floor(sqrt(k))^4.at n=43A363498