A050997 -id:A050997 - cp's OEIS frontend

A258602 a(n) is the index m such that A069492(m) = prime(n)^5.

2, 5, 12, 20, 37, 45, 68, 82, 106, 142, 154, 196, 219, 234, 260, 305, 342, 360, 407, 434, 451, 496, 528, 573, 635, 668, 681, 720, 737, 770, 885, 919, 966, 984, 1065, 1087, 1139, 1193, 1228, 1283, 1331, 1348, 1440, 1455, 1484, 1509, 1624, 1731, 1767, 1789

Offset: 1

Reinhard Zumkeller, Jun 06 2015

nonn

A069492(a(n)) = A050997(n) = prime(n)^5;
A069492(m) mod prime(n) > 0 for m < a(n);
also smallest number m such that A258570(m) = prime(n):
A258570(a(n)) = A000040(n) and A258570(m) != A000040(n) for m < a(n).

			.   n |  p |  a(n) | A069492(a(n)) = A050997(n) = p^5
. ----+----+-------+---------------------------------
.   1 |  2 |     2 |            32
.   2 |  3 |     5 |           243
.   3 |  5 |    12 |          3125
.   4 |  7 |    20 |         16807
.   5 | 11 |    37 |        161051
.   6 | 13 |    45 |        371293
.   7 | 17 |    68 |       1419857
.   8 | 19 |    82 |       2476099
.   9 | 23 |   106 |       6436343
.  10 | 29 |   142 |      20511149
.  11 | 31 |   154 |      28629151
.  12 | 37 |   196 |      69343957
.  13 | 41 |   219 |     115856201
.  14 | 43 |   234 |     147008443
.  15 | 47 |   260 |     229345007
.  16 | 53 |   305 |     418195493
.  17 | 59 |   342 |     714924299
.  18 | 61 |   360 |     844596301
.  19 | 67 |   407 |    1350125107
.  20 | 71 |   434 |    1804229351
.  21 | 73 |   451 |    2073071593
.  22 | 79 |   496 |    3077056399
.  23 | 83 |   528 |    3939040643
.  24 | 89 |   573 |    5584059449
.  25 | 97 |   635 |    8587340257  .

Andrew Howroyd, Table of n, a(n) for n = 1..1000

Cf. A258570, A000040, A050997, A069492, A258599, A258600, A258601, A258603.

import Data.List (elemIndex); import Data.Maybe (fromJust)
a258602 = (+ 1) . fromJust . (`elemIndex` a258570_list) . a000040

\\ Gen(limit,k) defined in A036967.
a(n)=#Gen(prime(n)^5,5) \\ Andrew Howroyd, Sep 10 2024

from math import gcd
from sympy import prime, integer_nthroot, factorint
def A258602(n):
    c, m = 0, prime(n)**5
    for t in range(1,integer_nthroot(m,9)[0]+1):
        if all(d<=1 for d in factorint(t).values()):
            for u in range(1,integer_nthroot(s:=m//t**9,8)[0]+1):
                if gcd(t,u)==1 and all(d<=1 for d in factorint(u).values()):
                    for w in range(1,integer_nthroot(a:=s//u**8,7)[0]+1):
                        if gcd(u,w)==1 and gcd(t,w)==1 and all(d<=1 for d in factorint(w).values()):
                            for y in range(1,integer_nthroot(z:=a//w**7,6)[0]+1):
                                if gcd(w,y)==1 and gcd(u,y)==1 and gcd(t,y)==1 and all(d<=1 for d in factorint(y).values()):
                                    c += integer_nthroot(z//y**6,5)[0]
    return c # Chai Wah Wu, Sep 10 2024

a(11) onwards corrected by Chai Wah Wu and Andrew Howroyd, Sep 10 2024

A319075 Square array T(n,k) read by antidiagonal upwards in which row n lists the n-th powers of primes, hence column k lists the powers of the k-th prime, n >= 0, k >= 1.

Original entry on oeis.org

1, 2, 1, 4, 3, 1, 8, 9, 5, 1, 16, 27, 25, 7, 1, 32, 81, 125, 49, 11, 1, 64, 243, 625, 343, 121, 13, 1, 128, 729, 3125, 2401, 1331, 169, 17, 1, 256, 2187, 15625, 16807, 14641, 2197, 289, 19, 1, 512, 6561, 78125, 117649, 161051, 28561, 4913, 361, 23, 1, 1024, 19683, 390625, 823543, 1771561, 371293

Offset: 0

Omar E. Pol, Sep 09 2018

If n = p - 1 where p is prime, then row n lists the numbers with p divisors.

The partial sums of column k give the column k of A319076.

			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, ...
...

Rows 0-13: A000012, A000040, A001248, A030078, A030514, A050997, A030516, A092759, A179645, A179665, A030629, A079395, A030631, A138031.
Other rows n: A030635 (n=16), A030637 (n=18), A137486 (n=22), A137492 (n=28), A139571 (n=30), A139572 (n=36), A139573 (n=40), A139574 (n=42), A139575 (n=46), A173533 (n=52), A183062 (n=58), A183085 (n=60), A261700 (n=100).
Columns 1-15: A000079, A000244, A000351, A000420, A001020, A001022, A001026, A001029, A009967, A009973, A009975, A009981, A009985, A009987, A009991.
Main diagonal gives A093360.
Second diagonal gives A062457.
Third diagonal gives A197987.
Removing the 1's we have A182944/ A182945.
Cf. A006093, A319074, A319076.

PARI
```
T(n, k) = prime(k)^n;
```

T(n,k) = A000040(k)^n, n >= 0, k >= 1.

A069492 5-full numbers: if a prime p divides k then so does p^5.

Original entry on oeis.org

1, 32, 64, 128, 243, 256, 512, 729, 1024, 2048, 2187, 3125, 4096, 6561, 7776, 8192, 15552, 15625, 16384, 16807, 19683, 23328, 31104, 32768, 46656, 59049, 62208, 65536, 69984, 78125, 93312, 100000, 117649, 124416, 131072, 139968, 161051

Offset: 1

Benoit Cloitre, Apr 15 2002

a(m) mod prime(n) > 0 for m < A258602(n); a(A258602(n)) = A050997(n) = prime(n)^5. - Reinhard Zumkeller, Jun 06 2015

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 (terms n=148..10000 corrected by Andrew Howroyd)

Cf. A036967, A036966, A001694.
Cf. A050997.
Cf. A258602.

import Data.Set (singleton, deleteFindMin, fromList, union)
a069492 n = a069492_list !! (n-1)
a069492_list = 1 : f (singleton z) [1, z] zs where
   f s q5s p5s'@(p5:p5s)
     | m < p5 = m : f (union (fromList $ map (* m) ps) s') q5s p5s'
     | otherwise = f (union (fromList $ map (* p5) q5s) s) (p5:q5s) p5s
     where ps = a027748_row m
           (m, s') = deleteFindMin s
   (z:zs) = a050997_list
-- Reinhard Zumkeller, Jun 03 2015

for(n=1,250000,if(n*sumdiv(n,d,isprime(d)/d^5)==floor(n*sumdiv(n,d,isprime(d)/d^5)),print1(n,",")))

\\ Gen(limit,k) defined in A036967.
Gen(170000, 5) \\ Andrew Howroyd, Sep 10 2024

from math import gcd
from sympy import integer_nthroot, factorint
def A069492(n):
    def bisection(f,kmin=0,kmax=1):
        while f(kmax) > kmax: kmax <<= 1
        while kmax-kmin > 1:
            kmid = kmax+kmin>>1
            if f(kmid) <= kmid:
                kmax = kmid
            else:
                kmin = kmid
        return kmax
    def f(x):
        c = n+x
        for t in range(1,integer_nthroot(x,9)[0]+1):
            if all(d<=1 for d in factorint(t).values()):
                for u in range(1,integer_nthroot(s:=x//t**9,8)[0]+1):
                    if gcd(t,u)==1 and all(d<=1 for d in factorint(u).values()):
                        for w in range(1,integer_nthroot(a:=s//u**8,7)[0]+1):
                            if gcd(u,w)==1 and gcd(t,w)==1 and all(d<=1 for d in factorint(w).values()):
                                for y in range(1,integer_nthroot(z:=a//w**7,6)[0]+1):
                                    if gcd(w,y)==1 and gcd(u,y)==1 and gcd(t,y)==1 and all(d<=1 for d in factorint(y).values()):
                                        c -= integer_nthroot(z//y**6,5)[0]
        return c
    return bisection(f,n,n) # Chai Wah Wu, Sep 10 2024

Sum_{n>=1} 1/a(n) = Product_{p prime} (1 + 1/(p^4*(p-1))) = 1.0695724994489739263413712783666538355049945684326048537289707764272637... - Amiram Eldar, Jul 09 2020

A122616 Sums of 5th powers of primes.

Original entry on oeis.org

32, 64, 96, 128, 160, 192, 224, 243, 256, 275, 288, 307, 320, 339, 352, 371, 384, 403, 416, 435, 448, 467, 480, 486, 499, 512, 518, 531, 544, 550, 563, 576, 582, 595, 608, 614, 627, 640, 646, 659, 672, 678, 691, 704, 710, 723, 729, 736, 742, 755, 761, 768

Offset: 1

Jonathan Vos Post, Sep 21 2006

After a finite number of integers which cannot be written as a sum of 5th powers of primes, all integers can be so written.

Giovanni Resta, Table of n, a(n) for n = 1..10000

Cf. A000040, A050997.

ok[n_] := {} != Quiet@ IntegerPartitions[n, All, Prime[ Range@ PrimePi@ Max[2, n^(1/5)]]^5, 1]; Select[Range[768], ok] (* Giovanni Resta, Jun 12 2016 *)

a(n) = a*32 + b*243 + c*3125 + d*16807 + e*161051 + ... where a,b,c,d,e,... are nonnegative integers. Sumset of A050997 Fifth powers of primes.

Several missing terms from Giovanni Resta, Jun 12 2016

A133522 Smallest k such that p(n)^5 + k is prime where p(n) is the n-th prime.

Original entry on oeis.org

5, 8, 12, 4, 2, 6, 20, 22, 8, 8, 12, 22, 26, 30, 20, 20, 74, 52, 22, 26, 4, 22, 6, 42, 40, 8, 58, 44, 42, 8, 40, 6, 36, 28, 2, 28, 6, 4, 20, 14, 2, 12, 8, 46, 2, 40, 10, 4, 110, 12, 18, 44, 42, 6, 24, 20, 8, 28, 46, 2, 18, 6, 60, 36, 24, 2, 18, 4, 24, 48, 6, 30, 6, 6, 22, 6, 2, 6, 2, 40, 2

Offset: 1

Carl R. White, Sep 14 2007

			p(2)=3, 3^5 = 243; for odd k and n > 1, p(n)^r - k is even and thus not prime, so we only need consider even k.
for k = 2: 243 + 2 = 245, which is 5 * 7^2 and not prime.
for k = 4: 243 + 4 = 247, which is 13 * 19, also not prime.
for k = 6: 243 + 6 = 249, which is 3 * 83, also not prime.
for k = 8: 243 + 8 = 251, which is prime, so 8 is the smallest number that can be added to 243 to make another prime.
Hence a(2) = 8.

Cf. A050997, A054271, A091666, A133517, A133518, A133519, A133520, A133521, (A001223).

A060971 Number of fifth powers of primes <= 2^n.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 6, 6, 7, 8, 9, 9, 11, 11, 13, 15, 16, 18, 21, 23, 25, 29, 31, 34, 39, 44, 47, 54, 62, 68, 76, 86, 97, 107, 122, 137, 154, 172, 193, 217, 244, 275, 309, 349, 393, 442, 499, 564, 635, 712, 807, 914, 1028, 1163, 1315, 1482

Offset: 0

Labos Elemer, May 09 2001

nonn

			For n = 10: the 5th powers of primes not exceeding 2^10 = 1024 are 32 and 243, so a(10) = 2.

Cf. A000720, A007053, A018117, A036386, A050997, A060967, A060969, A060970.

Table[ PrimePi[ Floor[ 2^(g/5)//N ] ], {g, 0, 150} ]

a(5*n) = A007053(n). - Chai Wah Wu, Jan 23 2025

a(n) = A000720(A018117(n)). - Amiram Eldar, Mar 22 2025

Missing a(0)=0 inserted by Sean A. Irvine, Jan 09 2023

A130555 Numbers that are sums of sixth powers of two distinct primes.

Original entry on oeis.org

793, 15689, 16354, 117713, 118378, 133274, 1771625, 1772290, 1787186, 1889210, 4826873, 4827538, 4842434, 4944458, 6598370, 24137633, 24138298, 24153194, 24255218, 25909130, 28964378, 47045945, 47046610, 47061506, 47163530

Offset: 1

Jonathan Vos Post, Aug 09 2007

This is to 6th powers as A130292 is to fifth powers, A130873 is to 4th powers and A120398 is to cubes. These can never be prime, as sixth powers are cubes and the sum of cubes factorizations applies. There are semiprimes for values beginning a(1) = 793, a(2) = 15689 = 29 * 541, a(4) = 117713 = 53 * 2221, a(11) = 4826873 = 173 * 27901.

			a(1) = prime(1)^6 + prime(2)^6 = 2^6 + 3^6 = 64 + 729 = 793 = 13 * 61.

Vincenzo Librandi, Table of n, a(n) for n = 1..8000

Cf. A000040, A001014, A050997, A120398, A122616, A130873.

Select[Sort[Flatten[Table[Prime[n]^6 + Prime[k]^6, {n, 15}, {k, n - 1}]]], # <= Prime[15^6] &]
Union[Total/@Subsets[Prime[Range[20]]^6,{2}]] (* Harvey P. Dale, Mar 11 2012 *)

{A001014(A000040(i)) + A001014(A000040(j)) for i > j}.

A133541 Sum of fifth powers of five consecutive primes.

Original entry on oeis.org

181258, 552519, 1972133, 4445107, 10864643, 31214741, 59472599, 127396699, 240776801, 381348901, 590182759, 979749101, 1625329443, 2354069543, 3557186207, 5132070551, 6786946651, 9149078751, 12243523093, 16477457435

Offset: 1

Artur Jasinski, Sep 14 2007

nonn

			a(1)=181258 because 2^5+3^5+5^5+7^5+11^5=181258.

Cf. A034963, A133524, A133525, A133526, A133527, A133528, A133529, A133530, A133531, A133532, A069484, A133534, A133535, A133536, A133537, A034964, A133538, A133539, A133540, A133542, A133543.

a = 5; Table[Prime[n]^a + Prime[n + 1]^a + Prime[n + 2]^a + Prime[n + 3]^a + Prime[n + 4]^a, {n, 1, 100}]
Total/@Partition[Prime[Range[30]]^5,5,1] (* Harvey P. Dale, Dec 02 2017 *)

a(n) = A133527(n) + A050997(n+4). - Michel Marcus, Nov 09 2013

A138407 a(n) = p^4*(p-1), where p = prime(n).

Original entry on oeis.org

16, 162, 2500, 14406, 146410, 342732, 1336336, 2345778, 6156502, 19803868, 27705630, 67469796, 113030440, 143589642, 224465326, 410305012, 702806938, 830750460, 1329973986, 1778817670, 2044673352, 3038106318, 3891582322

Offset: 1

Artur Jasinski, Mar 19 2008

Vincenzo Librandi, Table of n, a(n) for n = 1..200
Index to sequences related to prime powers.

Cf. A000010, A030514, A050997, A065416.

[NthPrime((n))^5 - NthPrime((n))^4: n in [1..30] ]; // Vincenzo Librandi, Jun 17 2011

a = {}; Do[p = Prime[n]; AppendTo[a, p^5 - p^4], {n, 1, 50}]; a
f54[n_]:=Module[{c=Prime[n]},c^5-c^4]; Array[f54,30] (* Harvey P. Dale, Mar 29 2015 *)

forprime(p=2,1e3,print1(p^5-p^4", ")) \\ Charles R Greathouse IV, Jun 16 2011

a(n) = A000010(prime(n)^5). - R. J. Mathar, Oct 15 2017
From Amiram Eldar, Nov 22 2022: (Start)
a(n) = prime(n)^5 - prime(n)^4 = A050997(n) - A030514(n).
Product_{n>=1} (1 - 1/a(n)) = A065416. (End)

First Mathematica program corrected by Harvey P. Dale, Mar 29 2015

A275387 Numbers of ordered pairs of divisors d < e of n such that gcd(d, e) > 1.

Original entry on oeis.org

0, 0, 0, 1, 0, 2, 0, 3, 1, 2, 0, 8, 0, 2, 2, 6, 0, 8, 0, 8, 2, 2, 0, 18, 1, 2, 3, 8, 0, 15, 0, 10, 2, 2, 2, 24, 0, 2, 2, 18, 0, 15, 0, 8, 8, 2, 0, 32, 1, 8, 2, 8, 0, 18, 2, 18, 2, 2, 0, 44, 0, 2, 8, 15, 2, 15, 0, 8, 2, 15, 0, 49, 0, 2, 8, 8, 2, 15, 0, 32, 6, 2

Offset: 1

Michel Lagneau, Aug 03 2016

nonn

Number of elements in the set {(x, y): x|n, y|n, x < y, gcd(x, y) > 1}.
Every element of the sequence is repeated indefinitely, for instance:
a(n)=0 if n prime;
a(n)=1 if n = p^2 for p prime (A001248);
a(n)=2 if n is a squarefree semiprime (A006881);
a(n)=3 if n = p^3 for p prime (A030078);
a(n)=6 if n = p^4 for p prime (A030514);
a(n)=8 if n is a number which is the product of a prime and the square of a different prime (A054753);
a(n)=10 if n = p^5 for p prime (A050997);
a(n)=15 if n is in the set {A007304} union {64} = {30, 42, 64, 66, 70,...} = {Sphenic numbers} union {64};
a(n)=18 if n is the product of the cube of a prime (A030078) and a different prime (see A065036);
a(n)=21 if n = p^7 for p prime (A092759);
a(n)=24 if n is square of a squarefree semiprime (A085986);
a(n)=32 if n is the product of the 4th power of a prime (A030514) and a different prime (see A178739);
a(n)=36 if n = p^9 for p prime (A179665);
a(n)=44 if n is the product of exactly four primes, three of which are distinct (A085987);
a(n)=45 if n is a number with 11 divisors (A030629);
a(n)=49 if n is of the form p^2*q^3, where p,q are distinct primes (A143610);
a(n)=50 if n is the product of the 5th power of a prime (A050997) and a different prime (see A178740);
a(n)=55 if n if n = p^11 for p prime(A079395);
a(n)=72 if n is a number with 14 divisors (A030632);
a(n)=80 if n is the product of four distinct primes (A046386);
a(n)=83 if n is a number with 15 divisors (A030633);
a(n)=89 if n is a number with prime factorization pqr^3 (A189975);
a(n)=96 if n is a number that are the cube of a product of two distinct primes (A162142);
a(n)=98 if n is the product of the 7th power of a prime and a distinct prime (p^7*q) (A179664);
a(n)=116 if n is the product of exactly 2 distinct squares of primes and a different prime (p^2*q^2*r) (A179643);
a(n)=126 if n is the product of the 5th power of a prime and different distinct prime of the 2nd power (p^5*q^2) (A179646);
a(n)=128 if n is the product of the 8th power of a prime and a distinct prime (p^8*q) (A179668);
a(n)=150 if n is the product of the 4th power of a prime and 2 different distinct primes (p^4*q*r) (A179644);
a(n)=159 if n is the product of the 4th power of a prime and a distinct prime of power 3 (p^4*q^3) (A179666).
It is possible to continue with a(n) = 162, 178, 209, 224, 227, 238, 239, 260, 289, 309, 320, 333,...

			a(12) = 8 because the divisors of 12 are {1, 2, 3, 4, 6, 12} and GCD(d_i, d_j)>1 for the 8 following pairs of divisors: (2,4), (2,6), (2,12), (3,6), (3,12), (4,6), (4,12) and (6,12).

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Cf. A001248, A006881, A007304, A030078, A030514, A030632, A046386, A050997, A054753, A063647, A065036, A066446, A079395, A085986, A085987, A092759, A143610, A162142, A178739, A178740, A179644, A179646, A179664, A189975.

Cf. A333976 (same with d <= e).

with(numtheory):nn:=100:
for n from 1 to nn do:
x:=divisors(n):n0:=nops(x):it:=0:
for i from 1 to n0 do:
  for j from i+1 to n0 do:
   if gcd(x[i],x[j])>1
    then
    it:=it+1:
    else
   fi:
  od:
od:
  printf(`%d, `,it):
od:

Table[Sum[Sum[(1 - KroneckerDelta[GCD[i, k], 1]) (1 - Ceiling[n/k] + Floor[n/k]) (1 - Ceiling[n/i] + Floor[n/i]), {i, k - 1}], {k, n}], {n, 100}] (* Wesley Ivan Hurt, Jan 01 2021 *)

a(n)=my(d=divisors(n)); sum(i=2,#d, sum(j=1,i-1, gcd(d[i],d[j])>1)) \\ Charles R Greathouse IV, Aug 03 2016

a(n)=my(f=factor(n)[,2],t=prod(i=1,#f,f[i]+1)); t*(t-1)/2 - (prod(i=1,#f,2*f[i]+1)+1)/2 \\ Charles R Greathouse IV, Aug 03 2016

a(n) = A066446(n) - A063647(n).

a(n) = Sum_{d1|n, d2|n, d1Wesley Ivan Hurt, Jan 01 2021

cp's OEIS Frontend

A258602 a(n) is the index m such that A069492(m) = prime(n)^5.

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A319075 Square array T(n,k) read by antidiagonal upwards in which row n lists the n-th powers of primes, hence column k lists the powers of the k-th prime, n >= 0, k >= 1.

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A069492 5-full numbers: if a prime p divides k then so does p^5.

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Haskell

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A122616 Sums of 5th powers of primes.

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A133522 Smallest k such that p(n)^5 + k is prime where p(n) is the n-th prime.

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A060971 Number of fifth powers of primes <= 2^n.

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Mathematica

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A130555 Numbers that are sums of sixth powers of two distinct primes.

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Mathematica

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A133541 Sum of fifth powers of five consecutive primes.

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