A147641 Numbers B in the triples (A,B,C) that set a record in the L-function of the ABC conjecture if the search for C admits only the restricted integer subset of A009967 as described in A147642.
16, 512, 12005, 6436341
Offset: 1
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.
a(18) = 5 because 18 = 2 * 3^2 and 2 + 3 = 5. a(19) = 19 because 19 is prime. a(20) = 7 because 20 = 2^2 * 5 and 2 + 5 = 7.
a008472 = sum . a027748_row -- Reinhard Zumkeller, Mar 29 2012
[n eq 1 select 0 else &+[p[1]: p in Factorization(n)]: n in [1..100]]; // Vincenzo Librandi, Jun 24 2017
A008472 := n -> add(d, d = select(isprime, numtheory[divisors](n))): seq(A008472(i), i = 1..40); # Peter Luschny, Jan 31 2012 A008472 := proc(n) add( d, d= numtheory[factorset](n)) ; end proc: # R. J. Mathar, Jul 08 2012
Prepend[Array[Plus @@ First[Transpose[FactorInteger[#]]] &, 100, 2], 0] Join[{0}, Rest[Total[Transpose[FactorInteger[#]][[1]]]&/@Range[100]]] (* Harvey P. Dale, Jun 18 2012 *) (* Requires version 7.0+ *) Table[DivisorSum[n, # &, PrimeQ[#] &], {n, 75}] (* Alonso del Arte, Dec 13 2014 *) Table[Sum[p, {p, Select[Divisors[n], PrimeQ]}], {n, 1, 100}] (* Vaclav Kotesovec, May 20 2020 *)
sopf(n) = local(fac=factor(n)); sum(i=1,matsize(fac)[1],fac[i,1])
vector(100,n,vecsum(factor(n)[,1]~)) \\ Derek Orr, May 13 2015
A008472(n)=vecsum(factor(n)[,1]) \\ M. F. Hasler, Jul 18 2015
from sympy import primefactors def A008472(n): return sum(primefactors(n)) # Chai Wah Wu, Feb 03 2022
def A008472(n): return add(d for d in divisors(n) if is_prime(d)) print([A008472(i) for i in (1..40)]) # Peter Luschny, Jan 31 2012
[sum(prime_factors(n)) for n in range(1,74)] # Giuseppe Coppoletta, Jan 19 2015
Triangle begins as: 2; 23, 23; 2, 1054, 2; 2, 12165, 12165, 2; 2, 13133, 533412, 13133, 2; 2, 14101, 6422240, 6422240, 14101, 2; 2, 15069, 12779580, 270482476, 12779580, 15069, 2; 2, 16037, 19605432, 3385203976, 3385203976, 19605432, 16037, 2; 2, 17005, 26899796, 9577346548, 137413443860, 9577346548, 26899796, 17005, 2;
f:= func< n,j | Round(((3-(-1)^n)/2)*NthPrime(j)^(n-1) - 2^((3-(-1)^n)/2)) >; function T(n,k,p,q,j) if n eq 2 then return NthPrime(j); elif (n eq 3 and k eq 2 or n eq 4 and k eq 2 or n eq 4 and k eq 3) then return f(n,j); elif (k eq 1 or k eq n) then return 2; else return T(n-1,k,p,q,j) + T(n-1,k-1,p,q,j) + (p*j+q)*NthPrime(j)*T(n-2,k-1,p,q,j); end if; return T; end function; [T(n,k,2,3,9): k in [1..n], n in [1..12]]; // G. C. Greubel, Mar 06 2021
T[n_, k_, p_, q_, j_]:= T[n,k,p,q,j]= If[n==2, Prime[j], If[n==3 && k==2 || n==4 && 2<=k<=3, ((3-(-1)^n)/2)*Prime[j]^(n-1) -2^((3-(-1)^n)/2), If[k==1 || k==n, 2, T[n-1,k,p,q,j] + T[n-1,k-1,p,q,j] + (p*j+q)*Prime[j]*T[n-2,k-1,p,q,j] ]]]; Table[T[n,k,2,3,9], {n,12}, {k,n}]//Flatten (* modified by G. C. Greubel, Mar 06 2021 *)
@CachedFunction def f(n,j): return ((3-(-1)^n)/2)*nth_prime(j)^(n-1) - 2^((3-(-1)^n)/2) def T(n,k,p,q,j): if (n==2): return nth_prime(j) elif (n==3 and k==2 or n==4 and 2<=k<=3): return f(n,j) elif (k==1 or k==n): return 2 else: return T(n-1,k,p,q,j) + T(n-1,k-1,p,q,j) + (p*j+q)*nth_prime(j)*T(n-2,k-1,p,q,j) flatten([[T(n,k,2,3,9) for k in (1..n)] for n in (1..12)]) # G. C. Greubel, Mar 06 2021
The corner of the square array is as follows: A000079 A000244 A000351 A000420 A001020 A001022 A001026 A000012 1, 1, 1, 1, 1, 1, 1, ... A000040 2, 3, 5, 7, 11, 13, 17, ... A001248 4, 9, 25, 49, 121, 169, 289, ... A030078 8, 27, 125, 343, 1331, 2197, 4913, ... A030514 16, 81, 625, 2401, 14641, 28561, 83521, ... A050997 32, 243, 3125, 16807, 161051, 371293, 1419857, ... A030516 64, 729, 15625, 117649, 1771561, 4826809, 24137569, ... A092759 128, 2187, 78125, 823543, 19487171, 62748517, 410338673, ... A179645 256, 6561, 390625, 5764801, 214358881, 815730721, 6975757441, ... ...
T(n, k) = prime(k)^n;
T(2,0) = 23^2 + 23^0 = 530. Table begins: 2; 24, 46; 530, 552, 1058; 12168, 12190, 12696, 24334; 279842, 279864, 280370, 292008, 559682; ...
With[{nn=30},Take[Union[Total/@Tuples[23^Range[0,nn],2]],nn]] (* Harvey P. Dale, Oct 16 2017 *)
from math import isqrt def A073215(n): return 23**(a:=(k:=isqrt(m:=n<<1))+(m>k*(k+1))-1)+23**(n-1-(a*(a+1)>>1)) # Chai Wah Wu, Apr 09 2025
C= 23 is the first candidate (and therefore by definition a record). Scanning the pairs (A,B) for this C we have L-values of L(1,22,23) = 0.5035, L(2,21,23) = 0.456, ... L(6,17,23) = 0.404, L(7,16,23) = 0.542 ,... L(11,12,23) = 0.428. The largest L-value stems from (A=7,B=16) which means the representative triple of the first record is (A,B,C) = (7,16,23). C= 23^2= 529 is the next candidate. Scanning again all (A,B) values subject to the constraints we achieve L(17,512,529) = 0.941... (Smaller ones like L(81,448,529) = 0.9123... are discarded). Since the L-value for C=529 is larger than the L-value for C=23, the next record is C=529 with representatives (A,B,C)= (17,512,529). The third candidate is C= 23^3= 12167. This generates a maximum of L(162,12005,12167) = 1.1089... (smaller values like L(17,12150,12167) = 1.0039.. discarded) which is again larger than the maximum of the previous record (which was 0.941..) So the C-value of 12167 is again a record-holder.
Numerator of 1, 2/23, -1054/529, -6340/12167, 3332716/279841, 33496312/6436343, -17563075016/148035889, -247760738608/3404825447, 129576612091280/78310985281...
[Numerator((&+[(-1)^k*Factorial(n)*(2/23)^(n-2*k)/( Factorial(k) *Factorial(n-2*k)): k in [0..Floor(n/2)]])): n in [0..30]]; // G. C. Greubel, Jun 09 2018
A159858 := proc(n) orthopoly[H](n,1/23) ; numer(%) ; end proc: # R. J. Mathar, Feb 16 2014
Numerator[Table[HermiteH[n, 1/23], {n, 0, 30}]] (* Vladimir Joseph Stephan Orlovsky, Jun 22 2011 *)
a(n)=numerator(polhermite(n,1/23)) \\ Charles R Greathouse IV, Jan 29 2016
[46^n: n in [0..20]]; // Vincenzo Librandi, Nov 21 2010
46^Range[0,20] (* or *) NestList[46#&,1,20] (* Harvey P. Dale, Jan 15 2017 *)
NestList[Mod[23*#, 10^8 + 1] &, 1, 50] (* Paolo Xausa, May 26 2025 *)
Comments