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A100897 a(n) is the decimal expansion of 7nn7. 5
7007, 7117, 7227, 7337, 7447, 7557, 7667, 7777, 7887, 7997, 710107, 711117, 712127, 713137, 714147, 715157, 716167, 717177, 718187, 719197, 720207, 721217, 722227, 723237, 724247, 725257, 726267, 727277, 728287, 729297, 730307 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Daniel Starodubtsev, Table of n, a(n) for n = 0..10000

FORMULA

a(n) = 7nn7.

EXAMPLE

If n=6, 7nn7 is 7667.

If n=15, 7nn7 is 715157 (a prime)

If n=18, 7nn7 is 718187 (a prime)

If n=19, 7nn7 is 719197 (a prime)

MAPLE

a:= n-> parse(cat(7, n, n, 7)):

seq(a(n), n=0..35);  # Alois P. Heinz, Jan 24 2020

MATHEMATICA

Table[idn=IntegerDigits[n]; FromDigits[Join[{7}, idn, idn, {7}]], {n, 0, 30}] (* Harvey P. Dale, May 14 2013 *)

CROSSREFS

Cf. A100846.

Sequence in context: A050663 A114615 A209879 * A206757 A236061 A317399

Adjacent sequences:  A100894 A100895 A100896 * A100898 A100899 A100900

KEYWORD

nonn,base,easy

AUTHOR

Parthasarathy Nambi, Jan 10 2005

STATUS

approved

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Last modified November 30 20:17 EST 2021. Contains 349425 sequences. (Running on oeis4.)