20541

Appears in sequences

• Numbers k such that sigma(k) = sigma(k+4).at n=24A015863
• a(n) = (n + 2)*(2*n^2 - n + 3)/6.at n=39A056520
• Numbers n such that n | 3^n + 2^n + 1^n.at n=23A056645
• Number of distinct values of multinomial coefficients ( n / (p1, p2, p3, ...) ) where (p1, p2, p3, ...) runs over all partitions of n.at n=46A070289
• 27-gonal numbers: a(n) = n*(25*n-23)/2.at n=41A255186
• Numbers of the form HMMSS with primes H < 24 and MM, SS < 60, for which the number of seconds after midnight, 3600*H+60*MM+SS, is also prime.at n=13A295011
• Number of n X 2 0..1 arrays with every element equal to 0, 2, 3 or 4 king-move adjacent elements, with upper left element zero.at n=9A297909
• T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 2, 3 or 4 king-move adjacent elements, with upper left element zero.at n=56A297915
• T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 2, 3, 4 or 6 king-move adjacent elements, with upper left element zero.at n=56A298328
• T(n,k) = Number of n X k 0..1 arrays with every element equal to 0, 2, 3, 4 or 7 king-move adjacent elements, with upper left element zero.at n=56A298508
• T(n,k) = Number of n X k 0..1 arrays with every element equal to 0, 2, 3, 4, 6 or 7 king-move adjacent elements, with upper left element zero.at n=56A299221
• T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 2, 3, 4, 6, 7 or 8 king-move adjacent elements, with upper left element zero.at n=56A300035