A069614 -id:A069614 - cp's OEIS frontend

A069621 a(1) = 9; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n). Alternate left and right concatenation yielding primes.

9, 97, 197, 1973, 31973, 319733, 3319733, 331973311, 6331973311, 633197331131, 5633197331131, 563319733113127, 6563319733113127, 65633197331131279, 3465633197331131279, 346563319733113127933, 18346563319733113127933

Offset: 1

Amarnath Murthy, Mar 27 2002

			a(4) = 1973 starting with a(3) =197 and a(5) = 31973 ending in a(4) = 1973.

Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A069613, A069614, A069615, A069616, A069617, A069618, A069619, A069620.

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

A069628 a(1) = 1; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits) in a(2n).

Original entry on oeis.org

1, 11, 211, 2111, 22111, 2211109, 92211109, 9221110901, 29221110901, 2922111090137, 32922111090137, 3292211109013747, 73292211109013747, 7329221110901374771, 157329221110901374771, 15732922111090137477101

Offset: 1

Amarnath Murthy, Mar 27 2002

Cf. A069614 to A069621, A069628 to A069636.

a[n_] := (j = ToString[n]; l = {"1", "3", "7", "9", "01", "03", "07", "09"}; k = 1; While[p = ToExpression[ StringJoin[j, ToString[l[[k]] ]]]; k < 9 && ! PrimeQ[p], k++ ]; If[k < 9, Return[p]]; i = IntegerDigits[n]; k = 11; While[p = FromDigits[Join[i, IntegerDigits[k]]]; ! PrimeQ[p], k++ ]; Return[p]); b[n_] := (i = IntegerDigits[n]; k = 1; While[p = FromDigits[ Join[ IntegerDigits[k], i]]; !PrimeQ[p], k++ ]; Return[p]); f[1] = 1; f[n_] := If[ EvenQ[n], a[f[n - 1]], b[f[n - 1]]]; Table[ f[n], {n, 1, 18}]

Edited and extended by Robert G. Wilson v, Apr 03 2002

A069636 a(1) = 9; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits)in a(2n).

Original entry on oeis.org

9, 97, 197, 1973, 31973, 319733, 3319733, 331973303, 5331973303, 533197330313, 9533197330313, 953319733031321, 3953319733031321, 395331973303132171, 12395331973303132171, 1239533197330313217121, 391239533197330313217121

Offset: 1

Amarnath Murthy, Mar 27 2002

Robert Israel, Table of n, a(n) for n = 1..348

Cf. A069614 to A069621, A069628 to A069636.

A[1]:= 9:
for n from 2 to 30 do
  if n::even then
    for d from 1 do
      x:= nextprime(A[n-1]*10^d);
      if x < (A[n-1]+1)*10^d then A[n]:= x; break fi
    od
  else
    d:=ilog10(A[n-1])+1;
    for x from A[n-1]+10^d by 10^d do
      if isprime(x) then A[n]:= x; break fi
    od
  fi
od:
seq(A[i],i=1..30); # Robert Israel, Nov 11 2020

Edited and extended by Robert G. Wilson v, Apr 03 2002

A069613 a(1) = 1; a(2n) is smallest prime starting with a(2n-1) and a number with no insignificant zeros, and a(2n+1) is smallest prime ending in a(2n-1). Alternate left and right concatenation yielding primes.

Original entry on oeis.org

1, 11, 211, 2111, 22111, 2211127, 12211127, 122111279, 14122111279, 1412211127927, 211412211127927, 21141221112792721, 1321141221112792721, 132114122111279272169, 27132114122111279272169, 2713211412211127927216947

Offset: 1

Amarnath Murthy, Mar 27 2002

a(6) is not 2211109 because the 0 in this number is considered insignificant (for comparison, the 0 in 22111109 would be significant, but this value is not the smallest possible extension of a(5)=22111). - Sean A. Irvine, May 07 2024

			a(4) = 2111 starting with a(3) =211 and a(5) = 22111 ending in a(4) = 2111.

Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A069614.

More terms from Robert Gerbicz, Aug 27 2002

Name clarified by Sean A. Irvine, May 07 2024

A069615 a(1) = 3; a(2n) = smallest prime starting (in the most significant digits) with a(2n-1) (i.e., as a right concatenation of a(2n-1) and a number with no insignificant zeros); a(2n+1) = smallest prime ending in (the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

Original entry on oeis.org

3, 31, 131, 1319, 21319, 213193, 12213193, 122131939, 1122131939, 112213193957, 27112213193957, 271122131939573, 3271122131939573, 327112213193957339, 2327112213193957339, 232711221319395733969, 13232711221319395733969

Offset: 1

Amarnath Murthy, Mar 27 2002

			a(4) = 1319 starting with a(3) = 131 and a(5) = 21319 ending in a(4) = 1319.

Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A069613, A069614.

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

A069616 a(1) = 4; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

Original entry on oeis.org

4, 41, 241, 2411, 32411, 324113, 6324113, 63241133, 1563241133, 15632411339, 815632411339, 81563241133919, 281563241133919, 2815632411339191, 322815632411339191, 32281563241133919151, 432281563241133919151

Offset: 1

Amarnath Murthy, Mar 27 2002

			a(4) = 2411 starting with a(3) =241 and a(5) = 32411 ending in a(4) = 2411.

Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A069613, A069614, A069615.

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

A069617 a(1) = 5; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

Original entry on oeis.org

5, 53, 353, 3533, 33533, 3353321, 113353321, 1133533213, 101133533213, 10113353321311, 310113353321311, 3101133533213117, 143101133533213117, 14310113353321311739, 314310113353321311739, 314310113353321311739103

Offset: 1

Amarnath Murthy, Mar 27 2002

			a(4) = 3533 starting with a(3) = 353 and a(5) = 33533 ending in a(4) = 3533.

Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A069613, A069614, A069615, A069616.

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

A069618 a(1) = 6; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

Original entry on oeis.org

6, 61, 461, 46133, 246133, 2461337, 22461337, 224613371, 12224613371, 1222461337117, 151222461337117, 15122246133711733, 615122246133711733, 615122246133711733213, 9615122246133711733213, 961512224613371173321349

Offset: 1

Amarnath Murthy, Mar 27 2002

			a(4) = 46133 starting with a(3) = 461 and a(5) = 246133 in a(4) = 46133.

Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A069613, A069614, A069615, A069616, A069617.

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

A069619 a(1) = 7; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

Original entry on oeis.org

7, 71, 271, 2711, 52711, 5271121, 135271121, 1352711219, 271352711219, 27135271121911, 1227135271121911, 122713527112191161, 20122713527112191161, 20122713527112191161109, 2720122713527112191161109

Offset: 1

Amarnath Murthy, Mar 27 2002

			a(4) = 2711 starting with a(3) = 271 and a(5) = 52711 in a(4) = 2711.

Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A069613, A069614, A069615, A069616, A069617, A069618.

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

A069620 a(1) = 8; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

Original entry on oeis.org

8, 83, 283, 2833, 32833, 328331, 2328331, 232833127, 3232833127, 323283312749, 14323283312749, 1432328331274927, 281432328331274927, 28143232833127492741, 3628143232833127492741, 36281432328331274927411

Offset: 1

Amarnath Murthy, Mar 27 2002

			a(4) = 2833 starting with a(3) = 283 and a(5) = 32833 ending in a(4) = 2833.

Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A069613, A069614, A069615, A069616, A069617, A069618, A069619.

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

cp's OEIS Frontend

A069621 a(1) = 9; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n). Alternate left and right concatenation yielding primes.

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A069628 a(1) = 1; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits) in a(2n).

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A069636 a(1) = 9; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits)in a(2n).

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A069613 a(1) = 1; a(2n) is smallest prime starting with a(2n-1) and a number with no insignificant zeros, and a(2n+1) is smallest prime ending in a(2n-1). Alternate left and right concatenation yielding primes.

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A069616 a(1) = 4; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

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A069617 a(1) = 5; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

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A069618 a(1) = 6; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

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A069619 a(1) = 7; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

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A069620 a(1) = 8; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n-1). Alternate left and right concatenation yielding primes.

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