Per H. Lundow has authored 75 sequences. Here are the ten most recent ones:
A185122
a(n) = minimum pandigital prime in base n.
Original entry on oeis.org
2, 11, 283, 3319, 48761, 863231, 17119607, 393474749, 10123457689, 290522736467, 8989787252711, 304978405943587, 11177758345241723, 442074237951168419, 18528729602926047181, 830471669159330267737, 39482554816041508293677, 1990006276023222816118943, 105148064265927977839670339, 5857193485931947477684595711
Offset: 2
The corresponding base-b representations are:
2 10
3 102
4 10123
5 101234
6 1013425
7 10223465
8 101234567
9 1012346785
10 10123457689
11 1022345689a7
12 101234568a79b
13 10123456789abc
14 10123456789cdab
15 10223456789adbce
...
-
from math import gcd
from itertools import count
from sympy import nextprime
from sympy.ntheory import digits
def A185122(n):
m = n
j = 0
if n > 3:
for j in range(1,n):
if gcd((n*(n-1)>>1)+j,n-1) == 1:
break
if j == 0:
for i in range(2,n):
m = n*m+i
elif j == 1:
for i in range(1,n):
m = n*m+i
else:
for i in range(2,1+j):
m = n*m+i
for i in range(j,n):
m = n*m+i
m -= 1
while True:
if len(set(digits(m:=nextprime(m),n)[1:]))==n:
return m # Chai Wah Wu, Mar 12 2024
A028449
Number of perfect matchings in graph P_{2} X P_{5} X P_{n}.
Original entry on oeis.org
1, 8, 450, 14320, 535229, 19114420, 692276437, 24972353440, 901990734650, 32567565264292, 1176040842289105, 42466317504553328, 1533458728878759825, 55373015618048484484, 1999515562849410856778, 72202339448101503740768, 2607220750517054436937621
Offset: 0
- Per Hakan Lundow, "Computation of matching polynomials and the number of 1-factors in polygraphs", Research report, No 12, 1996, Department of Math., Umea University, Sweden.
A033526
Number of matchings in graph P_{2} X P_{3} X P_{n}.
Original entry on oeis.org
1, 22, 1511, 90040, 5493583, 334056618, 20324827981, 1236501116120, 75226160041933, 4576591071807054, 278429681683117411, 16939044773645481920, 1030533959174319758227, 62695402974582513118434, 3814249420035058238741393, 232050484511869215926762256
Offset: 0
- Per Hakan Lundow, "Computation of matching polynomials and the number of 1-factors in polygraphs", Research reports, No 12, 1996, Department of Mathematics, Umea University.
A033527
Number of matchings in graph P_{2} X P_{4} X P_{n}.
Original entry on oeis.org
1, 71, 21497, 5493583, 1441534384, 376940962215, 98618371821449, 25799240154157639, 6749345823947488233, 1765694380951147363456, 461922949276035424430681, 120843562204869252316712655, 31613858308925485200467329841, 8270494656919429771594190182151
Offset: 0
- Per Hakan Lundow, "Computation of matching polynomials and the number of 1-factors in polygraphs", Research reports, No 12, 1996, Department of Mathematics, Umea University.
A033528
Number of matchings in graph P_{2} X P_{5} X P_{n}.
Original entry on oeis.org
1, 228, 305184, 334056618, 376940962215, 423657524608288, 476450515130518749, 535774070372040050788, 602492787376187496898304, 677518242019979197787376936, 761886547661136372157201911987, 856760801962209647160995669509984, 963449325363457811035756544808212891
Offset: 0
- Per Hakan Lundow, "Computation of matching polynomials and the number of 1-factors in polygraphs", Research reports, No 12, 1996, Department of Mathematics, Umea University.
A033529
Number of matchings in graph P_{2} X P_{6} X P_{n}.
Original entry on oeis.org
1, 733, 4334009, 20324827981, 98618371821449, 476450515130518749, 2303329608950881340608, 11134067093100203643948181, 53821768256990554940684650505, 260172308883754886843036887611589, 1257663186848063684537091601425009561
Offset: 0
- Per Hakan Lundow, "Computation of matching polynomials and the number of 1-factors in polygraphs", Research reports, No 12, 1996, Department of Mathematics, Umea University.
A033530
Number of matchings in graph P_{3} X P_{3} X P_{n}.
Original entry on oeis.org
1, 131, 90040, 49793133, 28579431833, 16294017491392, 9303034425177393, 5309783310438438755, 3030852157018381983096, 1729989715204411185894125, 987471788038820650012763705, 563644449821238971691233574464, 321725839534452657823357410831785
Offset: 0
- Per Hakan Lundow, "Computation of matching polynomials and the number of 1-factors in polygraphs", Research reports, No 12, 1996, Department of Mathematics, Umea University.
A033531
Number of matchings in graph P_{3} X P_{4} X P_{n}.
Original entry on oeis.org
1, 823, 5493583, 28579431833, 154620656140976, 831415352314053207, 4475746196648151844135, 24088698990102061728597981, 129653063594088631745065442153, 697826352881007761016861345617984, 3755891812799886342646421870514820641
Offset: 0
- Per Hakan Lundow, "Computation of matching polynomials and the number of 1-factors in polygraphs", Research reports, No 12, 1996, Department of Mathematics, Umea University.
A033533
Number of matchings in graph P_{4} X P_{4} X P_{n}.
Original entry on oeis.org
1, 10012, 1441534384, 154620656140976, 17312701462385916505, 1926836037115087006553088, 214664979834173287380956088153, 23911146651705731250582573707211200
Offset: 0
- Per Hakan Lundow, "Computation of matching polynomials and the number of 1-factors in polygraphs", Research reports, No 12, 1996, Department of Mathematics, Umea University.
A033534
Number of matchings in graph P_{5} X P_{5} X P_{n}.
Original entry on oeis.org
1, 2810694, 423657524608288, 42127221925485860896792, 4435122353330774501960785797973, 463310369790129032480118384076035223552
Offset: 0
- Per Hakan Lundow, "Computation of matching polynomials and the number of 1-factors in polygraphs", Research reports, No 12, 1996, Department of Mathematics, Umea University.
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