19476

Appears in sequences

• Number of discordant permutations.at n=15A000561
• a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = (natural numbers >= 2), t = (Lucas numbers).at n=15A024310
• a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n-k+1), where k = [ n/2 ], s = (natural numbers >= 2), t = (Lucas numbers).at n=14A024873
• Gaps of 9 in sequence A038593 (upper terms).at n=17A038658
• Numbers k such that cototient(k) is a square and sets a new record for squares.at n=31A063753
• Values of m such that N=(am+1)(bm+1)(cm+1) is a 3-Carmichael number (A087788), where a,b,c = 1,2,5.at n=32A064239
• Values of m such that N=(am+1)(bm+1)(cm+1) is a 3-Carmichael number (A087788), where a,b,c = 1,2,7.at n=18A064240
• Values of m such that N=(am+1)(bm+1)(cm+1) is a 3-Carmichael number (A087788), where a,b,c = 1,2,15.at n=38A064244
• Values of m such that N=(am+1)(bm+1)(cm+1) is a 3-Carmichael number (A087788), where a,b,c = 1,2,21.at n=25A064247
• a(1) = 1; a(n) = smallest number of the form k*a(n-1) +1 divisible by n^2.at n=5A069020
• Row sums of triangle A144334, binomial transform of [1, 2, 6, 7, 3, 0, 0, 0, ...].at n=19A144335
• The number of functions in a finite set that can be expressed by a composition power of another function. (It differs from A163948, as it excludes self compositions).at n=5A163950
• Coefficients of the sum 1+ x/(1-x) + x^2/(1-x^2) + x^3/ ( (1-x)(1-x^2)) + x^4/ ( (1-x)(1-x^3) ) + x^5/ ( (1-x)(1-x^4) ) + x^5 /((1-x^2)(1-x^3)) + x^6/ ( (1-x)(1-x^2)(1-x^3)) + ...at n=46A178702
• Third differences of A000219.at n=21A191661
• q-expansion of modular form psi_0^6/t_{3B}^2.at n=15A198958
• a(n) = 324*n^2 - 804*n + 468 (n>=2).at n=7A304619