21249

Appears in sequences

• Number of symmetric plane partitions of n.at n=38A005987
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 80 ones.at n=22A031848
• Number of 3-rowed binary matrices with n ones and no zero columns, up to row and column permutation.at n=30A058053
• Numbers k such that A109631(k) - A109631(k+1) = A109631(k+2).at n=15A109715
• Cubeful numbers whose neighbors are also cubeful.at n=8A122692
• a(n) = 625*n - 1.at n=33A158374
• a(n) = 34*n^2 - 1.at n=24A158588
• a(n) = 1+2*(d1 + 1)*(d2 + 1)*...*(dk + 1), where d1, d2, ..., dk are the prime factors of the n-th Fermat pseudoprime to base 2 A001567(n).at n=22A216646
• Numbers with 3 or more prime factors (with multiplicity) such that every concatenation of their prime factors is prime.at n=25A217264
• Numbers with 4 or more prime factors (with multiplicity) such that every concatenation of their prime factors is prime.at n=0A217265
• Number of 5 X n 0..2 arrays with no element equal to the sum of elements to its left or one plus the sum of the elements above it, modulo 3.at n=11A239032
• O.g.f. satisfies A^4(z) = 1/(1 - z)*( BINOMIAL(BINOMIAL(A(z))) )^3.at n=4A258379
• Numbers x such that x = Sum_{i=1..k} (x mod d_(x+i)) for some k, where d_(x+i) is the aliquot parts of (x+i).at n=13A290469
• Number of strict integer partitions of 2*n with no subset summing to n.at n=39A321142
• a(n) is the number of unlabeled rank-3 graded lattices with 4 coatoms and n atoms.at n=31A322599
• Records in A353717.at n=24A353722
• Yu. V. Matiyasevich's Riemann Hypothesis test.at n=4A356468