18971

Appears in sequences

• Centered tetrahedral numbers.at n=30A005894
• Expansion of 1/(1-x^4-x^5-x^6-x^7-x^8-x^9-x^10-x^11-x^12-x^13).at n=37A017835
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 25 ones.at n=10A031793
• Expansion of series related to Liouville's Last Theorem: g.f. Sum_{t>=1} (-1)^(t+1) *x^(t*(t+1)/2) / ( (1-x^t)^7 * Product_{i=1..t} (1-x^i) ).at n=11A059824
• 24 'Reverse and Add' steps are needed to reach a palindrome.at n=4A065318
• Partial sums of A026905; the convolution of the natural numbers with the partition function.at n=21A085360
• C(2*n+4,4)-C(2*n,4).at n=15A085474
• Numbers that reach the fixed point 89 under iteration of f(x) = reverse(x) - maxdigit(x).at n=25A097155
• Numbers k such that 8*R_k - 5 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=22A099422
• Lucas pseudoprimes.at n=17A217120
• Strong Lucas pseudoprimes.at n=4A217255
• Erroneous version of A007002 found in the 1995 Encyclopedia of Integer Sequences.at n=10A220184
• Number of (n+2)X(4+2) 0..3 arrays with every 3X3 subblock row and diagonal sum equal to 0 1 3 6 or 7 and every 3X3 column and antidiagonal sum not equal to 0 1 3 6 or 7.at n=7A252301
• Least k such that the first n digits of the decimal expansion of the ratio of the perimeter of a regular k-gon to its diameter match those of Pi.at n=8A280926