A278571 Index of first occurrence of n in A278567.
1, 7, 42, 385, 436, 1530, 3180, 3625, 8208, 3767, 10116, 6699
Offset: 1
Crossrefs
Cf. A278567.
Extensions
a(12) corrected by Don Reble, Nov 27 2016
This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
Phi_0 = x; Phi_1 = x - 1; Phi_2 = x + 1; Phi_3 = x^2 + x + 1; Phi_4 = x^2 + 1; ... From _Wolfdieter Lang_, Oct 29 2013: (Start) The irregular triangle a(n,m) begins: n\m 0 1 2 3 4 5 6 7 8 9 10 11 12 ... 0: 0 1 1: -1 1 2: 1 1 3: 1 1 1 4: 1 0 1 5: 1 1 1 1 1 6: 1 -1 1 7: 1 1 1 1 1 1 1 8: 1 0 0 0 1 9: 1 0 0 1 0 0 1 10: 1 -1 1 -1 1 11: 1 1 1 1 1 1 1 1 1 1 1 12: 1 0 -1 0 1 13: 1 1 1 1 1 1 1 1 1 1 1 1 1 14: 1 -1 1 -1 1 -1 1 15: 1 -1 0 1 -1 1 0 -1 1 ... Phi_15(x) = (x^1 - 1)*((x^3 - 1)^(-1))*((x^5 - 1)^(-1))*(x^15 - 1) because mu(15) = mu(1) = +1 and mu(3) = mu(5) = -1. Hence Phi_15(x) = 1 - x + x^3 - x^4 + x^5 - x^7 + x^8, giving row n = 15. Example for the reduction via the squarefree kernel: Phi_12(x) = Phi_6(x^(12/6)) = Phi_6(x^2). By the formula with the Mobius function Phi_6(x) = Phi_2(x^3)/Phi_2(x) = 1 - x + x^2 and with x -> x^2 this becomes Phi_12(x) = 1 - x^2 + x^4. (End)
N:= 100: # to get coefficients up to cyclotomic(N,x) with(numtheory): for n from 0 to N do C:= cyclotomic(n,x); L[n]:= seq(coeff(C,x,i),i=0..degree(C)); od: A:= [seq](L[n],n=0..N): # note that A013595(n) = A[n+1] # Robert Israel, Apr 17 2014
Table[CoefficientList[x^KroneckerDelta[n] Cyclotomic[n, x], x], {n, 0, 15}] // Flatten (* Peter Luschny, Dec 27 2016 *)
row(n) = if (n==0, p=x, p = polcyclo(n)); Vecrev(p); \\ Michel Marcus, Dec 14 2015
r = 0; Do[If[# > r, r = #; Print[n]] &@ Max@ Abs@ CoefficientList[Cyclotomic[n, x], x], {n, 10^4}] (* Michael De Vlieger, May 20 2024 *)
print1(r=1); for(n=2,1e4, t=vecmax(abs(Vec(polcyclo(n)))); if(t>r, r=t; print1(", "n))) \\ Charles R Greathouse IV, Jun 28 2012
Phi(165) = x^80 + x^79 + x^78 - x^75 - x^74 - x^73 - x^69 - x^68 - x^67 + x^65 + 2x^64 + 2x^63 + x^62 - x^60 - x^59 - x^58 - x^54 - x^53 - x^52 + x^50 + 2x^49 + 2x^48 + 2x^47 + x^46 - x^44 - x^43 - x^42 - x^41 - x^40 - x^39 - x^38 - x^37 - x^36 + x^34 + 2x^33 + 2x^32 + 2x^31 + x^30 - x^28 - x^27 - x^26 - x^22 - x^21 - x^20 + x^18 + 2x^17 + 2x^16 + x^15 - x^13 - x^12 - x^11 - x^7 - x^6 - x^5 + x^2 + x + 1, with 2 as the coefficient of x^16 (among others), and this is the least k for which 2 appears, so a(2) = 165.
N:= 40: count:= 0: A:= Array(0..N): A[0]:= 4: for k from 1 while count < N do S:= select(t -> t::posint and t <= N and A[t] = 0, {coeffs(numtheory:-cyclotomic(k,x),x)}): if S <> {} then A[convert(S,list)]:= k; count:= count + nops(S); fi od: convert(A,list); # Robert Israel, Dec 23 2018
Table[k = 1; While[! MemberQ[CoefficientList[Cyclotomic[k, x], x], n], k++]; k, {n, 0, 9}] (* Michael De Vlieger, Sep 29 2015 *)
a(n)=my(k,v);while(!setsearch(Set(Vec(polcyclo(k++))),n),);k
Phi(105) = x^48 + x^47 + x^46 - x^43 - x^42 - 2x^41 - x^40 - x^39 + x^36 + x^35 + x^34 + x^33 + x^32 + x^31 - x^28 - x^26 - x^24 - x^22 - x^20 + x^17 + x^16 + x^15 + x^14 + x^13 + x^12 - x^9 - x^8 - 2x^7 - x^6 - x^5 + x^2 + x + 1, with -2 as the coefficient of x^7 (among others), and this is the least k for which -2 appears, so a(2) = 105.
Table[k = 1; While[! MemberQ[CoefficientList[Cyclotomic[k, x], x], -n], k++]; k, {n, 0, 9}] (* Michael De Vlieger, Sep 29 2015 *)
a(n)=my(k,v);while(!setsearch(Set(Vec(polcyclo(k++))),-n),);k
with(numtheory): b:= proc(n) option remember; local k; for k from 2+`if`(n=1, 1, b(n-1)) by 2 while bigomega(k)<>3 or nops(factorset(k))<>3 do od; k end: a:= n-> max(map(abs, [coeffs(cyclotomic(b(n), x))])): seq(a(n), n=1..120); # Alois P. Heinz, Nov 27 2016
b[n_] := b[n] = (For[k = 2 + If[n == 1, 1, b[n-1]], PrimeOmega[k] != 3 || PrimeNu[k] != 3, k += 2]; k); a[n_] := Max @ Abs @ CoefficientList[Cyclotomic[b[n], x], x]; Array[a, 120] (* Jean-François Alcover, Mar 28 2017, after Alois P. Heinz *)
C_x({1,2,3},x) = (-x^15 - 5*x^14 - 12*x^13 - 17*x^12 - 11*x^11 + 4*x^10 + 16*x^9 + 10*x^8 - 6*x^6)/(x^15 + 4*x^14 + 7*x^13 + 4*x^12 - 8*x^11 - 18*x^10 - 13*x^9 + 7*x^8 + 19*x^7 + 11*x^6 - 6*x^5 - 10*x^4 - 2*x^3 + 3*x^2 + 2*x - 1) with maximal coefficient abs(-17) in the numerator, so a(3) = 17.
C_x(s)={my(g=if(#s <1,1, sum(i=1,#s, C_x(s[^i])*x^(s[i]))/(1-sum(i=1,#s, x^(s[i]))))); return(g)} a(n)={vecmax(abs(Vec(numerator(C_x([1..n])))))}
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