19857

Appears in sequences

• Base 9 digits are, in order, the first n terms of the periodic sequence with initial period 3,0,2,1.at n=4A037770
• Numbers n such that n and the four successive integers produce primes if substituted for x in the polynomial 5x^2+5x+1. See A090562, A090563. Terms show that longer similar chains also exist.at n=14A090100
• Semiprimes in A103376.at n=20A103396
• Semiprimes in A103377.at n=19A103397
• Semiprimes in A103378.at n=20A103398
• Semiprimes in A103379.at n=19A103399
• Semiprimes in A103380.at n=20A103400
• G.f.: 1/(1 - x*(1-x^3)/(1 - x^2*(1-x^4)/(1 - x^3*(1-x^5)/(1 - x^4*(1-x^6)/(1 - ...))))), a continued fraction.at n=27A227360
• G.f. A(x) satisfies A(A(A(A(x)))) = x + 4*x^2 + 16*x^3.at n=8A372537