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.

A214629 Primes p such that the sum of the digits plus the product of the digits is a prime.

Original entry on oeis.org

11, 13, 19, 23, 29, 31, 37, 43, 53, 59, 61, 73, 79, 89, 97, 101, 223, 263, 283, 401, 409, 443, 601, 607, 809, 823, 829, 883, 1013, 1019, 1031, 1033, 1039, 1051, 1091, 1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151, 1163, 1171, 1181, 1187, 1193, 1213, 1231, 1259
Offset: 1

Views

Author

Keywords

Examples

			11 is in the sequence because A061762(11) = 3 is prime.
		

Crossrefs

Cf. A061762, A344032. Primes in A185300.

Programs

  • Maple
    f:= proc(n) local L;
       L:= convert(n,base,10);
       convert(L,`+`)+convert(L,`*`)
    end proc:
    select(p -> isprime(f(p)), [seq(ithprime(i),i=1..1000)]); # Robert Israel, May 07 2021
  • Mathematica
    f[n_] := Module[{in = IntegerDigits[n]}, Times @@ in + Plus @@ in];Select[Prime[Range[300]], PrimeQ[f[#]] &]

Formula

{p in A000040: A061762(p) in A000040}. - R. J. Mathar, Aug 13 2012

A214746 Numbers n such that (sum of the square of the decimal digits of n) + (product of the square of decimal digits of n) is prime.

Original entry on oeis.org

1, 11, 13, 16, 19, 29, 31, 37, 59, 61, 73, 79, 91, 92, 95, 97, 101, 102, 104, 106, 110, 120, 140, 160, 201, 203, 205, 207, 210, 225, 230, 238, 250, 252, 270, 283, 302, 308, 320, 328, 380, 382, 401, 405, 409, 410, 449, 450, 490, 494, 502, 504, 506, 508, 520
Offset: 1

Views

Author

Michel Lagneau, Aug 01 2012

Keywords

Examples

			283 is in the sequence because 2^2+8^2+3^2 + 2^2*8^2*3^2 = 77 + 2304 = 2381 is prime.
		

Crossrefs

Cf. A185300.

Programs

  • Magma
    dd:=func; [n: n in [1..520] | IsPrime(&+dd(n)+&*dd(n))]; // Bruno Berselli, Aug 02 2012
  • Maple
    A:= proc(n) add(d^2, d=convert(n, base, 10)) ; end proc:
    B:= proc(n) mul(d^2, d=convert(n, base, 10)) ; end proc:
    isA:= proc(n) isprime(A(n)+B(n)) ; end proc:
    for n from 1 to 1000 do if isA(n) then printf("%a, ", n) ; end if; end do:
  • PARI
    is(n)=my(v=eval(Vec(Str(n))));isprime(sum(i=1,#v,v[i]^2)+prod(i=1,#v,v[i]^2)) \\ Charles R Greathouse IV, Aug 02 2012
    

A215059 Numbers n such that (sum of factorial of decimal digits of n) + (product of factorial of decimal digits of n) is prime.

Original entry on oeis.org

1, 10, 11, 12, 13, 15, 20, 21, 30, 31, 50, 51, 1000, 1001, 1002, 1010, 1011, 1012, 1020, 1021, 1100, 1101, 1102, 1110, 1111, 1112, 1120, 1121, 1200, 1201, 1210, 1211, 1339, 1344, 1345, 1354, 1356, 1359, 1365, 1366, 1368, 1386, 1393, 1395, 1434, 1435, 1443
Offset: 1

Views

Author

Michel Lagneau, Aug 01 2012

Keywords

Examples

			1345 is in the sequence because (1! + 3! + 4! + 5! ) + (1! * 3! * 4! * 5!)  = 151 + 17280 = 17431 is prime.
		

Crossrefs

Cf. A185300.

Programs

  • Maple
    A:= proc(n) add(d!, d=convert(n, base, 10)) ; end proc:
    B:= proc(n) mul(d!, d=convert(n, base, 10)) ; end proc:
    isA:= proc(n) isprime(A(n)+B(n)) ; end proc:
    for n from 1 to 1500 do if isA(n) then printf("%a, ", n) ; end if; end do:
  • Mathematica
    fdpQ[n_]:=Module[{f=IntegerDigits[n]!},PrimeQ[Total[f]+Times@@f]]; Select[ Range[1500],fdpQ] (* Harvey P. Dale, Nov 26 2013 *)

A344021 Numbers k such that A061762(k) and k+A061762(k) are both prime.

Original entry on oeis.org

1, 12, 16, 32, 34, 54, 56, 78, 104, 106, 160, 232, 236, 250, 252, 298, 302, 304, 326, 328, 340, 362, 382, 388, 474, 490, 502, 508, 526, 560, 580, 610, 650, 656, 670, 676, 706, 740, 760, 838, 850, 890, 898, 928, 940, 980, 1004, 1006, 1024, 1028, 1042, 1048, 1082, 1084, 1152, 1190, 1192, 1246, 1248
Offset: 1

Views

Author

J. M. Bergot and Robert Israel, May 06 2021

Keywords

Examples

			a(3) = 16 is a term because A061762(16) = 1*6+1+6=13 is prime and 16+13=29 is prime.
		

Crossrefs

Programs

  • Maple
    f:= proc(n) local L;
    L:= convert(n,base,10);
    convert(L,`*`)+convert(L,`+`);
    end proc:
    filter:= proc(n) local t; t:= f(n); isprime(t) and isprime(n+t) end proc:
    select(filter, [1,seq(i,i=2..10000,2)]);
Showing 1-4 of 4 results.