cp's OEIS Frontend

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.

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A217599 Prime(n), where n is such that (Sum_{i=1..n} prime(i)^2) / n is an integer.

Original entry on oeis.org

2, 67, 157, 3217, 3637, 4201, 231947, 2790569, 30116309, 12021325961, 26144296151, 1380187561637, 6549419699279, 735325088697473, 1746583001138813, 68725636353488501
Offset: 1

Views

Author

Robert Price, Mar 19 2013

Keywords

Comments

a(16) > 3*10^15 if it exists. - Anders Kaseorg, Dec 02 2020
a(17) > 3.1*10^17. - Paul W. Dyson, Jan 16 2025

Examples

			a(2) = 67, because 67 is the 19th prime and the sum of the first 19 primes^2 = 24966 when divided by 19 equals 1314 which is an integer.
		

Crossrefs

Cf. A085450 = smallest m > 1 such that m divides Sum_{k=1..m} prime(k)^n.

Programs

  • Mathematica
    t = {}; sm = 0; Do[sm = sm + Prime[n]^2; If[Mod[sm, n] == 0, AppendTo[t, Prime[n]]], {n, 100000}]; t (* T. D. Noe, Mar 19 2013 *)
    k = 1; p = 2; s = 0; lst = {}; While[p < 1000000000, s = s + p^2; If[ Mod[s, k++] == 0, AppendTo[lst, p]]; p = NextPrime@ p]; lst (* Robert G. Wilson v, Mar 08 2015 *)
  • PARI
    n=s=0; forprime(p=2,1e9, if((s+=p^2)%n++==0, print1(p", "))) \\ Charles R Greathouse IV, Feb 06 2015

Extensions

a(13) from Willem Hengeveld, Nov 29 2020
a(14)-a(15) from Anders Kaseorg, Dec 02 2020
a(16) from Paul W. Dyson, Sep 03 2022

A128165 Numbers k such that k divides 1 plus the sum of the first k primes.

Original entry on oeis.org

1, 2, 6, 10, 20, 22, 28, 155, 488, 664, 992, 6162, 7840, 7975, 8793, 18961, 32422, 148220, 231625, 332198, 459121, 462932, 2115894, 8108930, 10336641, 11789731, 15500046, 23483195, 46571611, 48582404, 77033887, 105390951, 132421841, 229481560, 1224959312
Offset: 1

Views

Author

Alexander Adamchuk, Feb 22 2007

Keywords

Comments

a(44) > 4.4*10^10. - Robert Price, Dec 15 2013
a(50) > 10^14. - Bruce Garner, Jun 05 2021

Crossrefs

Cf. A085450 (smallest m > 1 such that m divides Sum_{k=1..m} prime(k)^n).

Programs

  • Mathematica
    k = 0; s = 1; p = 2; A128165 = {}; While[k < 247336000, If[Mod[s += p, ++k] == 0, AppendTo[A128165, k]; Print[{k, p}]]; p = NextPrime@ p]; A128165
  • PARI
    is(n)=sum(i=1,n,prime(i),1)%n==0 \\ Charles R Greathouse IV, Nov 07 2014
    
  • PARI
    n=0; s=1; forprime(p=2,1e9, s+=p; if(s%n++==0, print1(n", "))) \\ Charles R Greathouse IV, Nov 07 2014

Extensions

More terms from Ryan Propper, Apr 05 2007
a(34) from Robert G. Wilson v, Jan 21 2011
a(35) from Robert Price, Dec 15 2013

A217600 Sum of the squares of the first A111441(n) primes.

Original entry on oeis.org

4, 24966, 263736, 1401992410, 2040870112, 3054955450, 346739122490032, 499159078330000800, 539391065522650998496, 25318239660367402306502991202, 251882074412384639674100925616, 31734804589156174948658730855096778, 3209990334856119248883461357431048564, 3910080232300154696097509520638192488259772
Offset: 1

Views

Author

Robert Price, Mar 19 2013

Keywords

Comments

a(n) - A111441(a(n)) - 11 == 0 (mod 24) for n > 1. This is similar to the relation between A000027 and A024450. - Karl-Heinz Hofmann, Jan 11 2021

Crossrefs

Cf. A085450 (smallest m > 1 such that m divides Sum_{k=1..m} prime(k)^n).

Programs

Extensions

a(13) from Willem Hengeveld, Nov 29 2020
a(14) from Bruce Garner, Dec 16 2020
a(15) from Bruce Garner, Dec 24 2020

A217601 Integer averages of squares of first primes.

Original entry on oeis.org

4, 1314, 7128, 3081302, 4009568, 5312966, 16834447856, 2462344442400, 289274033242208, 46671783125431818542, 221000817555367050608, 618811172463743796896678, 13954866972387224169218132, 176536110349401666017009273532, 996528450408723697487070591774
Offset: 1

Views

Author

Robert Price, Mar 19 2013

Keywords

Examples

			a(2) = 1314 is the average of squares of first 19 primes (24966/19=1314).
		

Crossrefs

Cf. A085450 (smallest m > 1 such that m divides Sum_{k=1..m} prime(k)^n).

Programs

Formula

a(n) = A217600(n)/A111441(n).

Extensions

a(13) from Karl-Heinz Hofmann, Dec 08 2020
a(14) from Karl-Heinz Hofmann, Dec 26 2020
a(15) from Karl-Heinz Hofmann, Dec 27 2020

A233523 Prime(n), where n is such that (1+sum_{i=1..n} prime(i)) / n is an integer.

Original entry on oeis.org

2, 3, 13, 29, 71, 79, 107, 907, 3491, 4967, 7853, 61223, 80051, 81547, 90901, 211811, 381629, 1990007, 3220793, 4749637, 6725027, 6784937, 34463699, 143691323, 185831033, 213609173, 285336497, 442634651, 911588849, 953122843, 1548789581, 2153787017
Offset: 1

Views

Author

Robert Price, Dec 15 2013

Keywords

Comments

a(50) > 3475385758524527. - Bruce Garner, Jun 05 2021

Examples

			a(3) = 13, because 13 is the 6th prime and the sum of the first 6 primes+1 = 42 when divided by 6 equals 7 which is an integer.
		

Crossrefs

Cf. A085450 = smallest m > 1 such that m divides Sum_{k=1..m} prime(k)^n.

Programs

  • Mathematica
    t = {}; sm = 1; Do[sm = sm + Prime[n]; If[Mod[sm, n] == 0, AppendTo[t, Prime[n]]], {n, 100000}]; t (* Derived from A217599 *)
  • PARI
    is(n)=if(!isprime(n),return(0)); my(t=primepi(n),s); forprime(p=2,n,s+=Mod(p,t)); s==0 \\ Charles R Greathouse IV, Nov 30 2013

A233862 Prime(k), where k is such that (1 + Sum_{i=1..k} prime(i)^2) / k is an integer.

Original entry on oeis.org

2, 3, 5, 7, 13, 23, 37, 41, 101, 107, 197, 317, 1033, 2029, 2357, 2473, 2879, 5987, 6173, 35437, 56369, 81769, 195691, 199457, 793187, 850027, 1062931, 1840453, 2998421, 4217771, 6200923, 9914351, 10153807, 13563889, 18878099, 60767923, 118825361, 170244929
Offset: 1

Views

Author

Robert Price, Dec 16 2013

Keywords

Comments

a(51) > 1428199016921.
a(67) > 2407033812270611. - Bruce Garner, May 05 2021

Examples

			a(5) = 13, because 13 is the 6th prime and the sum of the first 6 primes^2+1 = 378 when divided by 6 equals 63 which is an integer.
		

Crossrefs

Cf. A085450 (smallest m > 1 such that m divides Sum_{k=1..m} prime(k)^n).

Programs

  • Mathematica
    t = {}; sm = 1; Do[sm = sm + Prime[n]^2; If[Mod[sm, n] == 0, AppendTo[t, Prime[n]]], {n, 100000}]; t (* Derived from A217599 *)
    Module[{nn=9600000},Prime[#]&/@Transpose[Select[Thread[{Range[nn], 1+ Accumulate[ Prime[Range[nn]]^2]}],IntegerQ[Last[#]/First[#]]&]][[1]]] (* Harvey P. Dale, Sep 09 2014 *)
  • PARI
    is(n)=if(!isprime(n),return(0)); my(t=primepi(n),s); forprime(p=2,n,s+=Mod(p,t)^2); s==0 \\ Charles R Greathouse IV, Nov 30 2013

A122102 a(n) = Sum_{k=1..n} prime(k)^4.

Original entry on oeis.org

16, 97, 722, 3123, 17764, 46325, 129846, 260167, 540008, 1247289, 2170810, 4044971, 6870732, 10289533, 15169214, 23059695, 35177056, 49022897, 69174018, 94585699, 122983940, 161934021, 209392342, 272134583, 360663864, 464724265, 577275146, 708354747, 849512908
Offset: 1

Views

Author

Alexander Adamchuk, Aug 20 2006

Keywords

Comments

a(n) is prime for n = {2,32,90,110,134,152,168,180,194,...} = A122127.

Crossrefs

Partial sums of A030514.

Programs

  • Magma
    [&+[NthPrime(k)^4: k in [1..n]]: n in [1..30]]; // G. C. Greubel, Oct 02 2019
    
  • Maple
    seq(add(ithprime(k)^4, k=1..n), n=1..30); # G. C. Greubel, Oct 02 2019
  • Mathematica
    Table[Sum[Prime[k]^4,{k,1,n}],{n,1,100}]
    Accumulate[Prime[Range[30]]^4] (* Harvey P. Dale, Aug 07 2021 *)
  • PARI
    a(n)=my(s);forprime(p=2,prime(n),s+=p^4); s \\ Charles R Greathouse IV, Aug 02 2013
    
  • Sage
    [sum(nth_prime(k)^4 for k in (1..n)) for n in (1..30)] # G. C. Greubel, Oct 02 2019

Formula

From Vladimir Shevelev, Aug 02 2013: (Start)
a(n) = 0.2*n^5*log(n)^4 + O(n^5*log(n)^3*log(log(n))). The proof is similar to proof for A007504(n) (see link of Shevelev).
A generalization: Sum_{i=1..n} prime(i)^k = 1/(k+1)*n^(k+1)*log(n)^k + O(n^(k+1)*log(n)^(k-1)*log(log(n))).
(End)

A128169 Numbers k such that k divides 1 + Sum_{j=1..k} prime(j)^5 = 1 + A122103(k).

Original entry on oeis.org

1, 2, 4, 6, 10, 12, 22, 58, 155, 363, 464, 665, 1146, 2870, 3048, 4019, 5931, 8724, 21503, 50439, 67560, 476281, 705570, 4050684, 6956459, 7443590, 10449928, 10799546, 15385564, 17735139, 83325458, 245271750, 255583775, 1395860516, 2921734534, 6255577368, 9050771725, 12062893218, 13689205205, 42254229197, 46440930382
Offset: 1

Views

Author

Alexander Adamchuk, Feb 22 2007, Feb 23 2007

Keywords

Comments

a(52) > 3*10^13. - Bruce Garner, Jun 05 2021
a(53) > 1.2*10^14. - Bruce Garner, Mar 28 2022

Crossrefs

Cf. A085450 (smallest m > 1 such that m divides Sum_{k=1..m} prime(k)^n).

Programs

  • Mathematica
    p = 2; k = 0; s = 1; lst = {}; While[k < 521330000, s = s + p^5; If[Mod[s, ++k] == 0, AppendTo[lst, k]; Print[{k, p}]]; p = NextPrime@ p]

Extensions

a(31) from Sean A. Irvine, Jan 19 2011
a(32)-a(33) from Robert G. Wilson v, Jan 20 2011
a(34)-a(41) from Robert Price, Dec 18 2013

A098561 Numbers n such that the sum of the squares of the first n primes is prime.

Original entry on oeis.org

2, 18, 26, 36, 68, 78, 144, 158, 164, 174, 192, 212, 216, 236, 264, 288, 294, 338, 344, 356, 384, 404, 416, 426, 500, 516, 518, 522, 534, 540, 548, 614, 678, 680, 782, 858, 866, 876, 878, 896, 900, 912, 950, 974, 996, 1064, 1080, 1082, 1100, 1122, 1158, 1160
Offset: 1

Views

Author

Rick L. Shepherd, Sep 14 2004

Keywords

Comments

a(n) must clearly be even.

Examples

			2 is a term as the sum of the squares of the first two primes is 2^2 + 3^2 = 13, which is prime.
		

Crossrefs

Cf. A098562 (corresponding primes), A024450 (sums of squares of primes), A098563 (sums of cubes of primes), A013916 (sums of primes).

Programs

  • Mathematica
    Select[Range[1000], PrimeQ[Sum[Prime[i]^2, {i, #}]] &] (* Carl Najafi, Aug 22 2011 *)

A098562 Primes that are the sum of the squares of the first k primes for some k.

Original entry on oeis.org

13, 20477, 75997, 239087, 2210983, 3579761, 29194283, 40002073, 45448471, 55600481, 77290091, 108095623, 114986483, 155637463, 226226771, 302920139, 324657881, 519681709, 551321299, 618359839, 797005427, 944007487, 1039681147, 1124764853, 1923614047, 2135308631
Offset: 1

Views

Author

Rick L. Shepherd, Sep 14 2004

Keywords

Comments

These are the primes arising in A098561.

Examples

			From _K. D. Bajpai_, Dec 15 2014: (Start)
13 is in the sequence because the sum of the squares of the first 2 primes is 2^2 + 3^2 = 4 + 9 = 13, which is prime.
20477 is in the sequence because the sum of the squares of the first 18 primes is 2^2 + 3^2 + 5^2 + ... + 59^2 + 61^2 = 4 + 9 + 25 + ... + 3481 + 3721 = 20477, which is prime.
(End)
		

Crossrefs

Cf. A098561 (corresponding n), A024450 (sum of squares of primes), A066525 (sums of cubes of primes), A013918 (sums of primes).
Cf. A000040, A006567. - Jonathan Vos Post, Aug 13 2009

Programs

  • Mathematica
    Select[Table[Sum[Prime[k]^2, {k, 1, n}], {n, 1000}], PrimeQ]  (* K. D. Bajpai, Dec 15 2014 *)
  • PARI
    s=0; forprime(p=2, 1e6, t=s+=p^2; if(isprime(t), print1(t,", "))) \\ K. D. Bajpai, Dec 15 2014

Extensions

a(24)-a(26) from K. D. Bajpai, Dec 15 2014
a(42) in b-file corrected by Andrew Howroyd, Feb 28 2018
Previous Showing 11-20 of 141 results. Next