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.

Showing 1-4 of 4 results.

A119891 Prime trio leaders: largest number of a prime trio.

Original entry on oeis.org

29, 47, 83, 137, 173, 191, 227, 263, 281, 317, 353, 443, 461, 599, 641, 797, 821, 887, 911, 977, 1019, 1091, 1109, 1163, 1181, 1217, 1307, 1361, 1433, 1451, 1499, 1523, 1613, 1697, 1721, 1787, 1811, 1877, 1901, 1949, 2027, 2063, 2081, 2153, 2207, 2243
Offset: 1

Views

Author

Luc Stevens (lms022(AT)yahoo.com), May 27 2006

Keywords

Comments

A prime trio is a set of three distinct prime numbers such that the third number is a 1-digit number which is the sum of the digits of the second number and the second number is the sum of the digits of the first number.

Examples

			443 is in the sequence because it is the largest number of the prime trio (443, 11, 2).
599 is the first term with sum of digits different from 11 (cf. A106754), namely 23 (cf. A106762). This sequence contains also all primes with sum of digits equal to 41, 43, 61 etc., but not 29, 47, ... since the second digit sum must be a single-digit prime, i.e., 2, 3, 5 or 7. - _M. F. Hasler_, Mar 09 2022
		

Crossrefs

Subsequence of A304367.
Cf. A000040 (primes), A007953 (sum of digits), A106754 (primes with s.o.d. = 11), A106762 (s.o.d.(p) = 23), A106774 (s.o.d.(p) = 41), A106775 (s.o.d.(p) = 43), A106787 (s.o.d.(p) = 61): subsequences.

Programs

  • Maple
    filter:= proc(n) local x,y;
      if not isprime(n) then return false fi;
      x:= convert(convert(n,base,10),`+`);
      if x < 10 or not isprime(x) then return false fi;
      y:= convert(convert(x,base,10),`+`);
      member(y,{2,3,5,7})
    end proc:
    select(filter, [seq(i,i=11..10000,2)]); # Robert Israel, May 21 2021
  • Mathematica
    ptQ[n_]:=Module[{c=NestList[Total[IntegerDigits[#]]&,n,2]},Length[ Union[c]] == 3&&And@@PrimeQ[c]]; Select[Prime[Range[500]],ptQ] (* Harvey P. Dale, Aug 15 2012 *)
  • PARI
    select( {is_A119891(n, s=sumdigits(n))=bittest(172, sumdigits(s)) && isprime(s) && s>9 && isprime(n)}, primes([1,2345])) \\ M. F. Hasler, Mar 09 2022

A119892 Prime quartet leaders: largest number of a prime quartet.

Original entry on oeis.org

2999, 3989, 4799, 4889, 5879, 5897, 5987, 6599, 6689, 6779, 6869, 6959, 6977, 7499, 7589, 7877, 7949, 8597, 8669, 8849, 8867, 9479, 9497, 9587, 9677, 9749, 9767, 9839, 9857, 9929, 12899, 13799, 13997, 14699, 14879, 14897, 14969, 15797, 15887, 15959
Offset: 1

Views

Author

Luc Stevens (lms022(AT)yahoo.com), May 27 2006

Keywords

Comments

A prime quartet is a set of four different prime numbers such that the fourth number is a 1-digit number which is the sum of the digits of the third number, the third number is the sum of the digits of the second number and the second number is the sum of the digits of the first number.
Different from A106766.
Comment from Joshua Zucker, Apr 24 2007, on the difference between this sequence and A106766: The digit sum must be the largest member of a prime trio, so the first number where the sequences differ must be with digit sum 47 and thus have at least 6 digits - so until then you get all the primes with 4 or 5 digits that have digit sum 29.
a(2322)=389999 is the first value different from A106766, where A106766(2322)=390359. See also A106778 = primes with digit sum = 47: A106778(1)=389999. - Martin Fuller and Ray Chandler, Apr 24 2007
The sequence of prime quintet leaders is probably too large for the OEIS; its first term is the 334-digit prime 5*10^333-10^330-10^328-1 with sum of digits a(1) = 2999. - Charles R Greathouse IV, Mar 11 2022

Examples

			2999 is in the sequence because it is the largest number of the prime quartet (2999,29,11,2).
		

Crossrefs

Programs

  • Mathematica
    pqQ[n_]:=Module[{p1=NestList[Total[IntegerDigits[#]]&,n,3]},AllTrue[ Take[ p1,3],#>9&]&&AllTrue[p1,PrimeQ]]; Select[Range[16000],pqQ] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Oct 02 2020 *)
  • PARI
    DigitSum(n,b=10)=local(x);x=0;while(n,x+=n%b;n\=b);x
    PrimeEnsemble(n,b=10)=local(x);x=1;while(ispseudoprime(n),if(n=4, print1(p", "))); \\ Martin Fuller

A119890 Prime duet leaders: largest number of a prime duet.

Original entry on oeis.org

11, 23, 41, 43, 61, 101, 113, 131, 151, 223, 241, 311, 313, 331, 401, 421, 601, 1013, 1031, 1033, 1051, 1103, 1123, 1213, 1231, 1301, 1303, 1321, 2003, 2111, 2113, 2131, 2203, 2221, 2311, 3011, 3121, 3301, 4001, 4003, 4021, 4111, 4201, 5011, 5101, 10103
Offset: 1

Views

Author

Luc Stevens (lms022(AT)yahoo.com), May 27 2006

Keywords

Comments

A prime duet is a pair of two different prime numbers such that the second number is a 1-digit number which is the sum of the digits of the first number.
The terms of the sequence must be at least 2 digits in length, so {5,5} is not a prime duet. - Harvey P. Dale, May 07 2021

Examples

			113 is in the sequence because it is the largest number of the prime duet (113,5)
		

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[5,1300]],IntegerLength[Total[IntegerDigits[#]]]==1&&PrimeQ[Total[IntegerDigits[#]]]&] (* Harvey P. Dale, May 07 2021 *)
  • PARI
    \\ See PARI link. David A. Corneth, May 07 2021

Extensions

Corrected by Harvey P. Dale, May 07 2021

A119893 Prime soloists for which the sum of the digits is another prime soloist.

Original entry on oeis.org

67, 89, 139, 157, 179, 193, 197, 199, 229, 269, 283, 337, 359, 373, 379, 409, 449, 463, 467, 487, 557, 571, 577, 593, 607, 643, 647, 661, 683, 719, 733, 739, 751, 757, 773, 809, 823, 827, 829, 863, 881, 883, 919, 937, 953, 971, 991, 1039, 1093, 1097, 1129
Offset: 1

Views

Author

Luc Stevens (lms022(AT)yahoo.com), May 28 2006

Keywords

Examples

			67 is in the sequence because (1) it is a prime soloist and (2) the sum of its digits 6+7=13 is another prime soloist ( see A119889)
		

Crossrefs

Cf. A119889.
Showing 1-4 of 4 results.