A030156 -id:A030156 - cp's OEIS frontend

A030153 Numbers k such that in k and k^2 the parity of digits alternates.

0, 1, 2, 3, 4, 5, 6, 7, 9, 16, 23, 27, 36, 69, 74, 81, 96, 127, 181, 187, 296, 874, 2327, 2369, 2723, 2727, 2763, 3816, 4589, 5874, 6563, 6589, 6727, 8323, 10181, 12723, 18163, 18587, 21236, 21274, 29236, 29274, 30127, 43296, 52361, 78163, 87616

Offset: 1

Patrick De Geest

Giovanni Resta, Table of n, a(n) for n = 1..1226 (derived from A030154 b-file)

Cf. A030151, A030152, A030154, A030156, A030157, A030158.

altQ[n_] := n < 10 || Union[Total /@ Partition[ Mod[ IntegerDigits@n, 2], 2, 1]] == {1}; Select[ Range[0, 10^5], altQ[#] && altQ[#^2] &] (* Giovanni Resta, Aug 16 2018 *)

A030155 Odd n such that in n^2 the parity of digits alternates.

Original entry on oeis.org

1, 3, 5, 7, 9, 11, 13, 19, 23, 27, 31, 69, 81, 111, 113, 119, 127, 137, 181, 187, 237, 269, 273, 277, 281, 311, 461, 463, 539, 661, 673, 677, 689, 819, 831, 1019, 1027, 1111, 1113, 1119, 1127, 1137, 1269, 1277, 1287, 1361, 1369, 1377, 1863, 1969

Offset: 1

Patrick De Geest

Giovanni Resta, Table of n, a(n) for n = 1..10000

Cf. A030151, A030152, A030156, A030157, A030158.

altQ[n_] := n < 10 || Union[Total /@ Partition[ Mod[ IntegerDigits@n, 2], 2, 1]] == {1}; Select[ Range[1, 2000, 2], altQ[#^2] &] (* Giovanni Resta, Aug 16 2018 *)

Offset changed by Giovanni Resta, Aug 16 2018

A210251 Residues modulo 100 of odd squares.

Original entry on oeis.org

1, 9, 21, 25, 29, 41, 49, 61, 69, 81, 89

Offset: 1

M. F. Hasler, Mar 19 2012

Range of A016754. Odd terms from A010461. See also A002015, A008959, A174452.

Also the range of A030156 and A192775 without initial term.

Mod[#,100]&/@(Range[1,55,2]^2)//Union (* Harvey P. Dale, Jul 27 2017 *)

PARI
```
vecsort(vector(12,n,(2*n-1)^2)%100,,8)
```

{1,9} + {0,1,2,3,4}*20 union {25}.

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A030153 Numbers k such that in k and k^2 the parity of digits alternates.

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A030155 Odd n such that in n^2 the parity of digits alternates.

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Author

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Crossrefs

Programs

Mathematica

Extensions

A210251 Residues modulo 100 of odd squares.

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Author

Keywords

Crossrefs

Programs

Mathematica

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