A162908 -id:A162908 - cp's OEIS frontend

A162915 Absolute values of the first differences of A162908.

1, 1, 2, 2, 3, 2, 1, 2, 5, 4, 2, 2, 3, 2, 1, 2, 4, 5, 9, 7, 2, 4, 11, 10, 6, 5, 3, 2, 1, 2, 4, 5, 8, 9, 15, 12, 2, 5, 17, 16, 10, 8, 3, 2, 1, 3, 7, 6, 4, 7, 21, 17, 2, 3, 5, 7, 14, 13, 9, 7, 3, 4, 6, 4, 1, 5, 16, 17, 27, 23, 4, 8, 29, 24, 2, 4, 8, 7, 5, 7, 13, 14, 20, 16, 3, 2, 1, 7, 35, 32, 10, 11, 15

Offset: 1

Juri-Stepan Gerasimov, Jul 17 2009

Cf. A089229, A162361, A162908.

Corrected as a followup to correcting A162908. - R. J. Mathar, Jul 19 2009

A163117 The pairs of central digits of all primes with an even number of digits.

Original entry on oeis.org

1, 1, 1, 3, 1, 7, 1, 9, 2, 3, 2, 9, 3, 1, 3, 7, 4, 1, 4, 3, 4, 7, 5, 3, 5, 9, 6, 1, 6, 7, 7, 1, 7, 3, 7, 9, 8, 3, 8, 9, 9, 7, 0, 0, 0, 1, 0, 1, 0, 2, 0, 3, 0, 3, 0, 3, 0, 4, 0, 5, 0, 6, 0, 6, 0, 6, 0, 8, 0, 9, 0, 9, 0, 9, 1, 0, 1, 0, 1, 1, 1, 2, 1, 2, 1, 5, 1, 5, 1, 6, 1, 7, 1, 8, 1, 8, 1, 9, 2, 0, 2, 1, 2, 1, 2

Offset: 1

Juri-Stepan Gerasimov, Jul 21 2009

A subsequence of A033308.

			a(1)=1 and a(2)=1 represent the two digits of 11.
a(7)=1 and a(8)=9 represent the two digits of 19.
a(43)=0 and a(44)=0 represent the two zeros of the prime 1009.

Harvey P. Dale, Table of n, a(n) for n = 1..2000

Cf. A093339, A162908.

cd[n_]:=Module[{idn=IntegerDigits[n],len},len=IntegerLength[n]/2;Take[ idn,{len,len+1}]]; cd/@Select[Prime[Range[200]],EvenQ[ IntegerLength[ #]]&]//Flatten (* Harvey P. Dale, Jul 23 2018 *)

a(8) corrected by R. J. Mathar, Jul 27 2009

A163118 Absolute values of the first differences of A163117.

Original entry on oeis.org

0, 0, 2, 2, 6, 6, 8, 7, 1, 1, 7, 6, 2, 2, 4, 3, 3, 3, 1, 1, 3, 2, 2, 2, 4, 3, 5, 5, 1, 0, 6, 6, 4, 4, 2, 1, 5, 5, 1, 0, 2, 7, 0, 0, 1, 1, 1, 1, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 5, 5, 6, 6, 6, 6, 6, 6, 8, 8, 9, 9, 9, 9, 9, 8, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 4, 4, 4, 4, 5, 5, 6, 6, 7, 7, 7, 7, 8, 7, 2, 2, 1, 1, 1, 1, 0

Offset: 1

Juri-Stepan Gerasimov, Jul 21 2009

Cf. A093339, A162908, A163117.

a(n) = |A163117(n+1)-A163117(n)|.

a(7) and a(8) corrected by R. J. Mathar, Jul 31 2009

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A162915 Absolute values of the first differences of A162908.

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A163117 The pairs of central digits of all primes with an even number of digits.

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A163118 Absolute values of the first differences of A163117.

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