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.

Previous Showing 11-14 of 14 results.

A133223 Sum of digits of primes (A007605), sorted and with duplicates removed.

Original entry on oeis.org

2, 3, 4, 5, 7, 8, 10, 11, 13, 14, 16, 17, 19, 20, 22, 23, 25, 26, 28, 29, 31, 32, 34, 35, 37, 38, 40, 41, 43, 44, 46, 47, 49, 50, 52, 53, 55, 56, 58, 59, 61, 62, 64, 65, 67, 68, 70, 71, 73, 74, 76, 77, 79, 80, 82, 83, 85, 86, 88, 89, 91, 92, 94, 95, 97, 98, 100, 101, 103
Offset: 1

Views

Author

Lekraj Beedassy, Dec 19 2007

Keywords

Comments

Presumably this is 3 together with numbers greater than 1 and not divisible by 3 (see A001651). - Charles R Greathouse IV, Jul 17 2013. (This is not a theorem because we do not know if, given s > 3 and not a multiple of 3, there is always a prime with digit-sum s. Cf. A067180, A067523. - N. J. A. Sloane, Nov 02 2018)
From Chai Wah Wu, Nov 04 2018: (Start)
Conjecture: for s > 10 and not a multiple of 3, there exists a prime with digit-sum s consisting only of the digits 2 and 3 (cf. A137269). This conjecture has been verified for s <= 2995.
Conjecture: for s > 18 and not a multiple of 3, there exists a prime with digit-sum s consisting only of the digits 3 and 4. This conjecture has been verified for s <= 1345.
Conjecture: for s > 90 and not a multiple of 3, there exists a prime with digit-sum s consisting only of the digits 8 and 9. This conjecture has been verified for s <= 8995.
Conjecture: for 0 < a < b < 10, gcd(a, b) = 1 and ab not a multiple of 10, if s > 90 and s is not a multiple of 3, then there exists a prime with digit-sum s consisting only of the digits a and b. (End)

Crossrefs

Extensions

Corrected by Jeremy Gardiner, Feb 09 2014

A062340 Primes whose sum of digits is a multiple of 5.

Original entry on oeis.org

5, 19, 23, 37, 41, 73, 109, 113, 127, 131, 163, 181, 271, 307, 311, 389, 401, 433, 479, 523, 541, 569, 587, 613, 631, 659, 677, 811, 839, 857, 929, 947, 983, 997, 1009, 1013, 1031, 1063, 1103, 1117, 1153, 1171, 1289, 1301, 1423, 1487, 1531, 1559, 1621, 1667
Offset: 1

Views

Author

Amarnath Murthy, Jun 21 2001

Keywords

Examples

			569 is a prime with sum of digits = 20, hence belongs to the sequence.
		

Crossrefs

Cf. A007953 (sum of digits), A227793 (sum of digits divisible by 5).
Has as subsequence A062341 (primes with sum of digits s = 5), A107579 (s = 10), A106760 (s = 20), A106763 (s = 25), A106770 (s = 35), A106773 (s = 40), A106780 (s = 50), A106783 (s = 55), A107619 (s = 65) and A181321 (s = 70).
Cf. A062340 (equivalent for 8).

Programs

  • Magma
    [ p: p in PrimesUpTo(10000) | &+Intseq(p) mod 5 eq 0 ]; // Vincenzo Librandi, Apr 02 2011
    
  • Mathematica
    Select[Prime[Range[300]],Divisible[Total[IntegerDigits[#]],5]&] (* Harvey P. Dale, Jul 06 2020 *)
  • PARI
    select( {is_A062340(n)=sumdigits(n)%5==0&&isprime(n)}, primes([1,2000])) \\ M. F. Hasler, Mar 10 2022
  • Python
    from sympy import primerange as primes
    def ok(p): return sum(map(int, str(p)))%5 == 0
    print(list(filter(ok, primes(1, 1668)))) # Michael S. Branicky, May 19 2021
    

Formula

Intersection of A000040 (primes) and A227793 (sum of digits in 5Z). - M. F. Hasler, Mar 10 2022

Extensions

Corrected and extended by Harvey P. Dale and Larry Reeves (larryr(AT)acm.org), Jul 04 2001

A158283 Prime numbers p such that 1 = abs(final digit of p - sum of all the other digits of p).

Original entry on oeis.org

23, 43, 67, 89, 113, 157, 179, 199, 223, 269, 313, 337, 359, 379, 449, 607, 719, 739, 809, 829, 919, 1013, 1033, 1103, 1123, 1213, 1237, 1259, 1279, 1303, 1327, 1439, 1459, 1549, 1619, 1709, 2003, 2069, 2089, 2113, 2137, 2179, 2203, 2269, 2339, 2539
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Mar 15 2009

Keywords

Examples

			23(1=3-2), 43(1=abs(3-4)), 67(1=abs(7-6)), 89(1=abs(9-8)), 113(1=3-(1+1)).
		

Crossrefs

Programs

  • Mathematica
    ps1[n_]:=Module[{idn=IntegerDigits[n]},Abs[Last[idn]-Total[Most[idn]]] == 1]; Select[Prime[Range[400]],ps1] (* Harvey P. Dale, Jul 31 2012 *)

Extensions

Entries checked by R. J. Mathar, May 19 2010

A157715 Primes sorted on digit sums, then on the primes.

Original entry on oeis.org

2, 11, 101, 3, 13, 31, 103, 211, 1021, 1201, 2011, 3001, 10111, 20011, 20101, 21001, 100003, 102001, 1000003, 1011001, 1020001, 1100101, 2100001, 10010101, 10100011, 20001001, 30000001, 101001001, 200001001, 1000000021, 1000001011
Offset: 1

Views

Author

Lekraj Beedassy, Mar 04 2009

Keywords

Comments

Beyond n = 4, a(n) is believed to coincide with A062339.
Only correct for n >= 4 if an undiscovered prime of digit sum two (which would have to be a member of A080176) does not exist; this is conjectured but not proved. - Jeppe Stig Nielsen, Mar 30 2018

Examples

			There are only three primes with a digit sum of 2, and those are 2, 11, 101. Therefore these three primes are the first three terms of this sequence.
There is only one prime with a digit sum of 3, and that's 3 itself. Any higher number with a digit sum of 3 is a nontrivial multiple of 3 and therefore composite.
Then follows the first prime with a digit sum of 4, which is 13.
		

Crossrefs

Cf. A062341.

Programs

  • Mathematica
    Prime@ Flatten@ Values@ Take[KeySort@ PositionIndex[Total@ IntegerDigits@ # & /@ Prime@ Range[10^7]], 3] (* Michael De Vlieger, Apr 07 2018 *)

Extensions

Comment edited by Robert Israel, Dec 28 2015
Previous Showing 11-14 of 14 results.